Answer:
2y - 100
Step-by-step explanation:
Last year's income = y
2y-100
The figure below is a scale drawing of an office courtyard using the scale 1 centimeter = 4 feet.
Which figure is a scale drawing of the same courtyard using the scale 1 centimeter = 3 feet?
Using proportions, it is found that option A gives a figure that is a scale drawing of the same courtyard using the scale 1 centimeter = 3 feet.
What is a proportion?A proportion is a fraction of a total amount, and the measures are related using a rule of three. Due to this, relations between variables, either direct or inverse proportional, can be built to find the desired measures in the problem.
Researching this problem on the internet, the figure with a scale of 1 cm = 4 feet has the dimensions of:
51 cm, 75 cm, 30 cm and 72cm.
For a scale of 1 centimeter = 3 feet, these measures will be multiplied by 4/3, hence the figure is given in option A, as:
51 x 4/3 = 68 cm.75 x 4/3 = 100 cm.30 x 4/3 = 40 cm.72 x 4/3 = 96 cm.More can be learned about proportions at https://brainly.com/question/24372153
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a population of bobcats increase by 5% per year if the population is currently 40 in how many years will the population reach 80 round your answer to the nearest tenth. The population will reach 80 in about _____years
[tex]\qquad \textit{Amount for Exponential Growth} \\\\ A=P(1 + r)^t\qquad \begin{cases} A=\textit{accumulated amount}\dotfill & 80\\ P=\textit{initial amount}\dotfill &40\\ r=rate\to 5\%\to \frac{5}{100}\dotfill &0.05\\ t=years \end{cases} \\\\\\ 80=40(1 + 0.05)^{t}\implies \cfrac{80}{40}=1.05^t\implies 2=1.05^t\implies \log(2)=\log(1.05^t) \\\\\\ \log(2)=t\log(1.05)\implies \cfrac{\log(2)}{\log(1.05)}=t\implies 14.2\approx t[/tex]
A cone has one-third times the volume of a cylinder with the same base and
altitude.
A. True
B. False
Answer:
A cone has one -third times the volume of a cylinder with the same base and altitude. True
The answer is A. True.
Assuming the cylinder and cone have same base and altitude, the formulas are :
Cylinder = πr²hCone = 1/3πr²hBased on this, we can understand that :
A cone has one-third times the volume of a cylinder with the same base and altitude.
Hunter leaves his house to go on a bike ride. He starts at a speed of 15 km/hr. Hunter's
brother decides to join Hunter and leaves the house 30 minutes after him at a speed of
18 km/hr. How long will it take to Hunter's brother to catch up to him?
The time requires to catch up to him will be 3 hours.
What is speed?Speed is defined as the ratio of the time distance traveled by the body to the time taken by the body to cover the distance. Speed is a scalar quantity it does not require any direction only needs magnitude to represent.
Given that Hunter leaves his house to go on a bike ride. He starts at a speed of 15 km/hr. Hunter's brother decides to join Hunter and leaves the house 30 minutes after him at a speed of 18 km/hr.
The time will be calculated as below:-
30 minutes = 0.5 hour
15x = 18(x - 0.5)
15x = 18x - 9
-3x = -9
x = 3 hours
Therefore, the time requires to catch up to him will be 3 hours.
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Please help me answer this question
Answer: A
Step-by-step explanation:
The total value of the prizes is [tex]1000+500+2(50)=1600[/tex].
The total cost of the tickets is [tex]1000(4.00)=4000[/tex].
So, the total loss is $2400.
Dividing this by 1000 tickets gives $-2.40.
If a certain number, , is multiplied by 6, it will be equal to 4 less than thrice the same number. The correct equation for the above statement is?
The correct equation is [tex]x\cdot6=3x-4[/tex].
Let the number be [tex]x[/tex].
According to the question,
Number multiplied by [tex]6[/tex] [tex]=6x[/tex].
[tex]4[/tex] less than thrice the number [tex]=3x-4[/tex].
Hence, the correct equation will be [tex]x\cdot6=3x-4[/tex].
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The perimeter of a square is 72 inches. What is the length of each side
Consider the following figure:
Answer:
x=90
y=148
Step-by-step explanation:
Since we know a line is 180 degrees, and we know that angle Q is 90, x must be a 90-degree angle as well.
With our given information we can add up the two given angles in the triangle which are 90 and 58
90+58=148
To find what R is, we must subtract 148 from 180 because all the angles in a triangle sum up to 180.
180-148=32
Now that we know that R is 32, because we know that a line is 180 degrees, we can subtract 32 from 180 to get our final answer for y as 148.
180-32=148
Graph the line with a slope of −1 that contains the point (3,6).
Answer:
The equation of the line is y = -1.x + 9
Graph is provided in the attached figure
Step-by-step explanation:
The slope intercept equation of a line in 2D(x,y) coordinates is given by the equation
[tex]y = mx + c[/tex]
where m is the slope of the line and c the y-intercept i.e. where the line crosses the y axis at x = 0
Given slope = -1, we can find c and the equation of the line
Since (3,6) is a point on the graph, these coordinates must satisfy the above equation
Substitute for y = 6 and x = 3
[tex]6 = (-1)3 + c\\\\c = 9\\\\\textrm{Equation of line is }\\y = -1.x + 9 \\y = 9-x[/tex]
In the attached figure you can see that (3,6) is on the line
Name a pair of opposite rays on plane L.
Answer:
GD and GC
Step-by-step explanation:
Opposite rays lie on the same line and extend in opposite directions from the same end point. Rays are named by naming the end point first, then another point on the ray.
Opposite raysPoints D, G, C lie on the same line with point G between the other two. That means rays GD and GC are opposite rays.
Identify the coefficient -7x2 y4
The answer is -7.
The coefficient is the part of the variable that does not change with respect to the variable.
Hence, in the monomial -7x²y⁴, the coefficient is -7.
Solve for x. Please help I don’t understand how to do this
Answer:
x = 5
Step-by-step explanation:
There's a Secant Theorem that someone else figured out (waaaay back in history) we just need to memorize it. So a secant is a line that touches the circle in two places. Your picture has two secants that both go thru the same point that's outside the circle. The secants each have a bit that's inside the circle and a bit that's outside the circle. And we could add together the inside and outside bits and get a total for the whole thing.
The secant theorem says that the outside piece × the whole thing on one secant = the outside piece × the whole thing on the other secant.
For the secant on top the "outside" bit is 9 and the whole thing is (2x+1+9). We'll times these together.
For the bottom secant the outside piece is 10 and the whole thing is (x+3+10). We'll multiply these together.
9(2x+1+9)=10(x+3+10)
simplify.
9(2x+10) = 10(x+13)
distribute.
18x + 90 = 101x + 130
combine like terms.
8x + 90 = 130
subtract 90
8x = 40
divide by 8
x = 5
see image.
Consider the spiral curves given parametrically by: (see picture and answer question)
a. The arc length is given by the integral
[tex]L(r) = \displaystyle \int_3^\infty \sqrt{x'(t)^2 + y'(t)^2} \, dt \\\\ ~~~~~~~~ = \int_3^\infty \sqrt{\left(\frac{t\cos(t) - r\sin(t)}{t^{r+1}}\right)^2 + \left(-\frac{t\sin(t) + r\cos(t)}{t^{r+1}}\right)^2} \, dt \\\\ ~~~~~~~~ = \int_3^\infty \sqrt{\frac{(t^2+r^2)\cos^2(t) + (t^2+r^2)\sin^2(t)}{\left(t^{r+1}\right)^2}} \, dt \\\\ ~~~~~~~~ = \boxed{\int_3^\infty \frac{\sqrt{t^2+r^2}}{t^{r+1}} \, dt}[/tex]
b. The integrand roughly behaves like
[tex]\dfrac t{t^{r+1}} = \dfrac1{t^r}[/tex]
so the arc length integral will converge for [tex]\boxed{r>1}[/tex].
c. When [tex]r=3[/tex], the integral becomes
[tex]L(3) = \displaystyle \int_3^\infty \frac{\sqrt{t^2+9}}{t^4} \, dt[/tex]
Pull out a factor of [tex]t^2[/tex] from under the square root, bearing in mind that [tex]\sqrt{x^2} = |x|[/tex] for all real [tex]x[/tex].
[tex]L(3) = \displaystyle \int_3^\infty \frac{\sqrt{t^2} \sqrt{1+\frac9{t^2}}}{t^4} \, dt \\\\ ~~~~~~~~ = \int_3^\infty \frac{|t| \sqrt{1+\frac9{t^2}}}{t^4} \, dt \\\\ ~~~~~~~~ = \int_3^\infty \frac{t \sqrt{1+\frac9{t^2}}}{t^4} \, dt \\\\ ~~~~~~~~ = \int_3^\infty \frac{\sqrt{1+\frac9{t^2}}}{t^3} \, dt[/tex]
since for [tex]3\le t<\infty[/tex], we have [tex]|t|=t[/tex].
Now substitute
[tex]s=1+\dfrac9{t^2} \text{ and } ds = -\dfrac{18}{t^3} \, dt[/tex]
Then the integral evaluates to
[tex]L(3) = \displaystyle -\frac1{18} \int_2^1 \sqrt{s} \, ds \\\\ ~~~~~~~~ = \frac1{18} \int_1^2 s^{1/2} \, ds \\\\ ~~~~~~~~ = \frac1{27} s^{3/2} \bigg|_1^2 \\\\ ~~~~~~~~ = \frac{2^{3/2} - 1^{3/2}}{27} = \boxed{\frac{2\sqrt2-1}{27}}[/tex]
a) The improper integral in simplified form is equal to [tex]L = \int\limits^{\infty}_{3} {\frac{\sqrt{t^{2}+r^{2}}}{t^{r + 1}} } \, dt[/tex].
b) r > 1 for a spiral with finite length.
c) The length of the spiral when r = 3 is (1 - 2√2) / 9 units.
How to characterize and analyze a group of parametric functions
a) The arc length formula for 2-dimension parametric functions is defined below:
L = ∫ √[(dx / dt)² + (dy / dt)²] dt, for [α, β] (1)
If we know that [tex]\dot x (t) = \frac{t \cdot \cos t - r \cdot \sin t}{t^{r+1}}[/tex], [tex]\dot y(t) = \frac{t\cdot \sin t + r\cdot \cos t}{t^{r + 1}}[/tex], α = 0 and β → + ∞ then their arc length formula is:
[tex]L = \int\limits^{\infty}_{3} {\sqrt{\left(\frac{t\cdot \cos t - r\cdot \sin t}{t^{r + 1}}\right)^{2}+\left(\frac{t\cdot \sin t + r\cdot \cos t}{t^{r+1}}\right)^{2}} } \, dt[/tex]
By algebraic handling and trigonometric formulae (cos ² t + sin² t = 1):
[tex]L = \int\limits^{\infty}_{3} {\frac{\sqrt{t^{2}+r^{2}}}{t^{r + 1}} } \, dt[/tex] (2)
The improper integral in simplified form is equal to [tex]L = \int\limits^{\infty}_{3} {\frac{\sqrt{t^{2}+r^{2}}}{t^{r + 1}} } \, dt[/tex].
b) By ratio comparison criterion, we notice that √(t² + r²) is similar to √t² = t and [tex]\frac{\sqrt{t^{2}+r^{2}}}{t^{r + 1}}[/tex] is similar to [tex]\frac{t}{t^{r +1}} = \frac{1}{t^{r}}[/tex].
The integral found in part a) has a finite length if and only the governing grade of the denominator is greater that the governing grade of the numerator. and according to the ratio comparson criterion, the absolute value of the ratio is greater than 0 and less than 1. Therefore, r > 1 for a spiral with finite length.
c) Now we proceed to integrate the function:
L = ∫ [√(t² + 9) / t⁴] dt, for [3, + ∞].
L = ∫ [t · √(1 + 9 / t²) / t⁴] dt, for [3, + ∞].
By using the algebraic substitutions: u = 1 + 9 / t², du = - (18 / t³) dt → - (1 / 18) du.
L = ∫ √u du, for [3, + ∞].
L = - (1 / 9) · √(u³), for [3, + ∞].
L = - (1 / 9) · [√(1 + 9 / t²)³], for [3, + ∞].
L = - (1 / 9) · [√(2³) - √(1³)]
L = - (1 / 9) · (2√2 - 1)
L = (1 - 2√2) / 9
The length of the spiral when r = 3 is (1 - 2√2) / 9 units.
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would someone be able to assist me with this problem?
Answer:
a)
Step-by-step explanation:
Which of the following is not true about two integers p and q, where p is even and g is odd? A p+q is odd. B. pq is even C q +1 even. D. q + 5 is odd.
Answer:
The statement "q + 5 is odd" is FALSE.
Step-by-step explanation:
Let p = 2 and q = 3.
A. p + q is odd ... 2 + 3 = 5 TRUE
B. pq is even ... 2*3 = 6 TRUE
C. q + 1 is even ... 3 + 1 = 4 TRUE
D. q + 5 is odd ... 3 + 5 = 8 FALSE
Select the graph of the function g(x) = 4(0.6)x based on what you learned about its key features.
The picture below is the answer I got correct.
The graph of an exponential function shows a geometric increase or decrease using a curve
Exponential graphsExponential functions are inverse of logarithmic functions. The standard exponential function is expressed as:
y = ab^x
where
a is the base
x is the exponent
The graph of an exponential function shows a geometric increase or decrease using a curve. According to the function given there will a decrease rate due to the value of the rate value given which is less than 1. The graph of the function given is attached below;
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Copy the problems onto your paper, mark the given and prove the statements asked. Prove, triangle CAV is congruent to triangle CEV
Quadrilateral is a family of plane shapes that have four straight sides. Thus the sum of their internal angles is [tex]360^{o}[/tex]. Examples include rectangle, square, rhombus, trapezium, and kite.
A kite is a plane shape that has its adjacent sides to have equal measures.
The given diagram in the question is a kite that has its specific properties compared to other quadrilaterals.
Thus, the required proof is stated below:
Given: ΔCAV and ΔCEV
Prove that: ΔCAV ≅ ΔCEV
Then,
CE ≅ CA (length of side property of a kite)
EV ≅ AV (length of side property of a kite)
<ACV ≅ <ECV (bisected property of a given angle)
<AVC ≅ <EVC (bisected property of a given angle)
CV is a common side to ΔCAV and ΔCEV
Therefore it can be deduced that;
ΔCAV ≅ ΔCEV (Angle-Angle-Side congruent theorem)
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What is the length of S?
In politics, marketing, etc. we often want to estimate a percentage or proportion p. One calculation in statistical polling is the margin of error - the largest (reasonble) error that the poll could have. For example, a poll result of 72% with a margin of error of 4% indicates that p is most likely to be between 68% and 76% (72% minus 4% to 72% plus 4%).
In a (made-up) poll, the proportion of people who like dark chocolate more than milk chocolate was 43% with a margin of error of 1.9%. Describe the conclusion about p using an absolute value inequality.
The answer field below uses the symbolic entry option in Mobius. That lets you type in a vertical bar | to represent absolute values. Also, when you type in << and then, the symbolic entry option will automatically convert that to <.I the same way, if you type in> and then, the symbolic entry option will automatically convert that to >
Be sure to use decimal numbers in your answer (such as using 0.40 for 40%).
The absolute value inequality is given as |(p - 0.43)I ≤ 0.019
How to describe the proportion using the absolute value inequalityThe proportion p = 43% = 0.43
Margin of error = 1.9% = 0.019
The value of the proportion can then be said to lie between
(0.43 - 0.019) ≤ p ≤ (0.43 + 0.019)
In order to convert to the absolute inequality we would be having
-0.019 ≤ (p - 0.43) ≤ 0.019
I (p - 0.43)I ≤ 0.019
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There are 96 football players at all levels at Davenport High School. If two-thirds of the players make the honor roll for their grades how many olayers are on the list?
64 players
48 players
72 players
54 players
Define the linear programming problems. State the key terms in L.P.P.
Answer:
Step-by-step explanation:
Linear Programming Problems (LPP): Linear programming or linear optimization is a process which takes into consideration certain linear relationships to obtain the best possible solution to a mathematical model. It is also denoted as LPP. It includes problems dealing with maximizing profits, minimizing costs, minimal usage of resources, etc. These problems can be solved through the simplex method or graphical method.
Linear Programming For Class 12
Linear Programming
Linear Programming Worksheet
The Linear programming applications are present in broad disciplines such as commerce, industry, etc. In this section, we will discuss, how to do the mathematical formulation of the LPP.
Mathematical Formulation of Problem
Let x and y be the number of cabinets of types 1 and 2 respectively that he must manufacture. They are non-negative and known as non-negative constraints.
The company can invest a total of 540 hours of the labour force and is required to create up to 50 cabinets. Hence,
15x + 9y <= 540
x + y <= 50
The above two equations are known as linear constraints.
Let Z be the profit he earns from manufacturing x and y pieces of the cabinets of types 1 and 2. Thus,
Z = 5000x + 3000y
Our objective here is to maximize Z. Hence Z is known as the objective function. To find the answer to this question, we use graphs, which is known as the graphical method of solving LPP. We will cover this in the subsequent sections.
Graphical Method
The solution for problems based on linear programming is determined with the help of the feasible region, in case of graphical method. The feasible region is basically the common region determined by all constraints including non-negative constraints, say, x,y≥0, of an LPP. Each point in this feasible region represents the feasible solution of the constraints and therefore, is called the solution/feasible region for the problem. The region apart from (outside) the feasible region is called as the infeasible region.
The optimal value (maximum and minimum) obtained of an objective function in the feasible region at any point is called an optimal solution. To learn the graphical method to solve linear programming completely reach us.
Linear Programming Applications
Let us take a real-life problem to understand linear programming. A home décor company received an order to manufacture cabinets. The first consignment requires up to 50 cabinets. There are two types of cabinets. The first type requires 15 hours of the labour force (per piece) to be constructed and gives a profit of Rs 5000 per piece to the company. Whereas, the second type requires 9 hours of the labour force and makes a profit of Rs 3000 per piece. However, the company has only 540 hours of workforce available for the manufacture of the cabinets. With this information given, you are required to find a deal which gives the maximum profit to the décor company.
Linear Programming problem LPP
Given the situation, let us take up different scenarios to analyse how the profit can be maximized.
He decides to construct all the cabinets of the first type. In this case, he can create 540/15 = 36 cabinets. This would give him a profit of Rs 5000 × 36 = Rs 180,000.
He decides to construct all the cabinets of the second type. In this case, he can create 540/9 = 60 cabinets. But the first consignment requires only up to 50 cabinets. Hence, he can make profit of Rs 3000 × 50 = Rs 150,000.
He decides to make 15 cabinets of type 1 and 35 of type 2. In this case, his profit is (5000 × 15 + 3000 × 35) Rs 180,000.
Similarly, there can be many strategies which he can devise to maximize his profit by allocating the different amount of labour force to the two types of cabinets. We do a mathematical formulation of the discussed LPP to find out the strategy which would lead to maximum profit.
⬆️
Question is up there
Let [tex]n[/tex] be the total number of stickers. If she puts 21 stickers on a page, she will fill up [tex]p[/tex] pages such that
[tex]n = 21p + 14[/tex]
Suzanna has between 90 and 100 stickers, so
[tex]90 \le n \le 100 \implies 76 \le n - 14 \le 86[/tex]
[tex]n-14[/tex] is a multiple of 21, and 4•21 = 84 is the only multiple of 21 in this range. So she uses up [tex]p=4[/tex] pages and
[tex]n-14 = 4\cdot21 \implies n = 4\cdot21 + 14 = \boxed{98}[/tex]
stickers.
Decreasing the number of years of a loan decreases the amount of interest repaid over the term of the loan. Suppose a dental hygienist has the option of a 30-year loan or a 25-year loan of $345,000 at an annual interest rate of 3.75%.
(a)
a) Calculate the monthly payment (in dollars) for each loan. (Round your answers to the nearest cent.)
30-year loan
25-year loan
b) Calculate the savings in interest (in dollars) by using the 25-year loan. (Round your answer to the nearest cent.)
Answer:
a) 30 yr: $1597.75; 25 yr: $1773.75
b) $43065.00
Step-by-step explanation:
The monthly payment for each loan can be found using the amortization formula, or a spreadsheet or calculator. The shorter 25-year loan has fewer and larger payments, but the net result is less interest paid.
a)The attached calculator shows the monthly payments to be ...
30 year loan: $1597.75 monthly
25 year loan: $1773.75 monthly
b)The number of payments is the product of 12 payments per year and the number of years. The total repaid is the monthly payment times the number of payments.
The difference in amounts repaid is the difference in interest charged.
360×1597.75 -300×1773.75 = $43065 . . . . savings using 25-year loan
__
Additional comment
The monthly payment on a loan of principal P at annual rate r for t years is ...
A = P(r/12)/(1 -(1 +r/12)^(-12t))
Some calculators and all spreadsheets have built-in functions for calculating this amount.
Evaluate each expression if a=2,b=-3,C=-1, and d=4
5+d(3b-2d)
Answer:
it's simple, put the values in the equation.
5 + d( 3b-2d) = 5 + 4( 3×-3 - 2× 4)
= 5 + 4( -9-8)
= 5+ 4 × -17
= 5-68 = -63 ans.
I need help with question
Answer
square root of 128 Lies between two square numbe
121 = 11 ^ 2
(11.1) ^ 2 = 133.1
So, √128 lies between 11.0 and 11.1.
Option A: 11.0 and 11.1a. Based on the picture, what properties can you be sure this figure has? Think about angles, lines, and points.
b. Does ray l bisect ∠ABC? Explain your thinking.
c. What would you need to do to prove that ray l bisects ∠ABC?
The angle measures ABD = 45, DBC = 45 and ABC = 90 imply that ray l bisect ∠ABC?
The properties of the figureFrom the figure, we have the following highlights:
The lines AB and BC are perpendicular lines i.e. the angle at B =90Ray I bisects the angle ABC (because 45 + 45 = 90)Angles ABD and DBC are adjacent anglesThis means that the points ABC can be joined to form a right triangle
Does ray l bisect ∠ABC?Yes, it does.
This is so because it divides the angle ABC into equal segments.
i.e.
ABC = 90
DBC = 45
So, we have
ABD = 90 - 45
ABD = 45
The angle measures ABD = 45, DBC = 45 and ABC = 90 imply that ray l bisect ∠ABC?
What would you need to do to prove that ray l bisects ∠ABC?You would need the measures of ABC and ABD
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Find the area for the shaded polygon
Taking the distance between dots as 1 unit, we have;
Area of the blue shaded region = square 10 unitsArea of the yellow polygon = 6 square units Which method can be used to find the area of the shaded figures?Taking the figures as comprising of triangles and trapezoids, we have;
In the blue polygon, we have;
Trapezoid area = ((4 + 3)/2) × 2 = 7
Area of the unshaded triangles = 0.5 × 2 × 1 + 0.5 × 2 × 2 + 0.5 × 2 × 1 = 4
Square area = 3 × 2 = 6
Shaded triangle area = 0.5 × 2 × 1 = 1
Sum of the areas is therefore;
A = 7 - 4 + 6 + 1 = 10
Which gives;
Area of the blue shaded region = 10Area of the lower yellow trapezoid is found as follows;
Trapezoid area = ((2 + 3)/2) × 4 = 10
Unshaded triangle area = 0.5 × 2 × 1 + 0.5 × 3 × 3 = 5.5
Area of the top triangle = 0.5 × 3 × 1 = 1.5
Area of the shaded yellow polygon is therefore;
A = 10 - 5.5 + 1.5 = 6
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A vector U has initial point (-3,-2) and terminal point (-6,1) .
Write U in component form.
Answer:
<-3,3>
Step-by-step explanation:
Consider the ordinary differential equation (answer questions in picture)
a. Given the 2nd order ODE
[tex]y''(x) = 4y(x) + 4[/tex]
if we substitute [tex]z(x)=y'(x)+2y(x)[/tex] and its derivative, [tex]z'(x)=y''(x)+2y'(x)[/tex], we can eliminate [tex]y(x)[/tex] and [tex]y''(x)[/tex] to end up with the ODE
[tex]z'(x) - 2y'(x) = 4\left(\dfrac{z(x)-y'(x)}2\right) + 4[/tex]
[tex]z'(x) - 2y'(x) = 2z(x) - 2y'(x) + 4[/tex]
[tex]\boxed{z'(x) = 2z(x) + 4}[/tex]
and since [tex]y(0)=y'(0)=1[/tex], it follows that [tex]z(0)=y'(0)+2y(0)=3[/tex].
b. I'll solve with an integrating factor.
[tex]z'(x) = 2z(x) + 4[/tex]
[tex]z'(x) - 2z(x) = 4[/tex]
[tex]e^{-2x} z'(x) - 2 e^{-2x} z(x) = 4e^{-2x}[/tex]
[tex]\left(e^{-2x} z(x)\right)' = 4e^{-2x}[/tex]
[tex]e^{-2x} z(x) = -2e^{-2x} + C[/tex]
[tex]z(x) = -2 + Ce^{2x}[/tex]
Since [tex]z(0)=3[/tex], we find
[tex]3 = -2 + Ce^0 \implies C=5[/tex]
so the particular solution for [tex]z(x)[/tex] is
[tex]\boxed{z(x) = 5e^{-2x} - 2}[/tex]
c. Knowing [tex]z(x)[/tex], we recover a 1st order ODE for [tex]y(x)[/tex],
[tex]z(x) = y'(x) + 2y(x) \implies y'(x) + 2y(x) = 5e^{-2x} - 2[/tex]
Using an integrating factor again, we have
[tex]e^{2x} y'(x) + 2e^{2x} y(x) = 5 - 2e^{2x}[/tex]
[tex]\left(e^{2x} y(x)\right)' = 5 - 2e^{2x}[/tex]
[tex]e^{2x} y(x) = 5x - e^{2x} + C[/tex]
[tex]y(x) = 5xe^{-2x} - 1 + Ce^{-2x}[/tex]
Since [tex]y(0)=1[/tex], we find
[tex]1 = 0 - 1 + Ce^0 \implies C=2[/tex]
so that
[tex]\boxed{y(x) = (5x+2)e^{-2x} - 1}[/tex]
6.a) The differential equation for z(x) is z'(x) = 2z(x) + 4, z(0) = 3.
6.b) The value of z(x) is [tex]z(x) = 5e^{2x} - 2[/tex].
6.c) The value of y(x) is [tex]y(x) = \frac{5e^{2x}}{4} - \frac{1}{4e^{2x}} -1[/tex].
The given ordinary differential equation is y''(x) = 4y(x) + 4, y(0) = y'(0) = 1 ... (d).
We are also given a substitution function, z(x) = y'(x) + 2y(x) ... (z).
Putting x = 0, we get:
z(0) = y'(0) + 2y(0),
or, z(0) = 1 + 2*1 = 3.
Rearranging (z), we can write it as:
z(x) = y'(x) + 2y(x),
or, y'(x) = z(x) - 2y(x) ... (i).
Differentiating (z) with respect to x, we get:
z'(x) = y''(x) + 2y'(x),
or, y''(x) = z'(x) - 2y'(x) ... (ii).
Substituting the value of y''(x) from (ii) in (d) we get:
y''(x) = 4y(x) + 4,
or, z'(x) - 2y'(x) = 4y(x) + 4.
Substituting the value of y'(x) from (i) we get:
z'(x) - 2y'(x) = 4y(x) + 4,
or, z'(x) - 2(z(x) - 2y(x)) = 4y(x) + 4,
or, z'(x) - 2z(x) + 4y(x) = 4y(x) + 4,
or, z'(x) = 2z(x) + 4y(x) - 4y(x) + 4,
or, z'(x) = 2z(x) + 4.
The initial value of z(0) was calculated to be 3.
6.a) The differential equation for z(x) is z'(x) = 2z(x) + 4, z(0) = 3.
Transforming z(x) = dz/dx, and z = z(x), we get:
dz/dx = 2z + 4,
or, dz/(2z + 4) = dx.
Integrating both sides, we get:
∫dz/(2z + 4) = ∫dx,
or, {ln (z + 2)}/2 = x + C,
or, [tex]\sqrt{z+2} = e^{x + C}[/tex],
or, [tex]z =Ce^{2x}-2[/tex] ... (iii).
Substituting z = 3, and x = 0, we get:
[tex]3 = Ce^{2*0} - 2\\\Rightarrow C - 2 = 3\\\Rightarrow C = 5.[/tex]
Substituting C = 5, in (iii), we get:
[tex]z = 5e^{2x} - 2[/tex].
6.b) The value of z(x) is [tex]z(x) = 5e^{2x} - 2[/tex].
Substituting the value of z(x) in (z), we get:
z(x) = y'(x) + 2y(x),
or, 5e²ˣ - 2 = y'(x) + 2y(x),
which gives us:
[tex]y(x) = \frac{5e^{2x}}{4} - \frac{1}{4e^{2x}} -1[/tex] for the initial condition y(x) = 0.
6.c) The value of y(x) is [tex]y(x) = \frac{5e^{2x}}{4} - \frac{1}{4e^{2x}} -1[/tex].
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if x varies directly as y, and
X = 24 when y= 21, Find x when
Y=6
Answer:
x = 48/7
Step-by-step explanation:
There's two good ways to do this problem.
Option 1:
Translate "x varies directly as y" into the equation y=kx
Then you have to find k. After you "reset" your y=kx equation, fill in k and then solve for x. See image.
Option 2:
Translate "varies directly" into a proportion, which is two fractions equal to each other:
x/y = x/y
Fill in the three numbers given and cross multiply and solve to find the fourth number. See image.