Consider the differential equation: 2y′′−13y′−7y = 0


a. Show that, for any constants A and B, the following is a solution to the above differential equation: y = Ae^(−9x)+Be^(x/3)

b. Find the values A and B that make the above general solution into a solution for the following initial value problem: 2y′′−13y′−7y = 0; y(0) = 3, y′(0) = −5

Answers

Answer 1
a) Finding the derivatives and replacing into the equation, we reach an identity, an thus, for any value of the constants, [tex]y = Ae^{-7x} + Be^{\frac{x}{2}}[/tex] is a solution.b) Solving a system of equations, according to the conditions, we find that: [tex]A = -\frac{7}{15}, B = \frac{52}{15}[/tex]

--------------------------------------------------

Just a correction, the characteristic roots of the equation are [tex]y = 7[/tex] and [tex]y = -\frac{1}{2}[/tex], thus, we should test for:

[tex]y = Ae^{7x} + Be^{-\frac{x}{2}}[/tex]

--------------------------------------------------

Question a:

First, we find the derivatives, thus:

[tex]y = Ae^{7x} + Be^{-\frac{x}{2}}[/tex]

[tex]y^{\prime} = 7Ae^{-7x} - \frac{1}{2}Be^{-\frac{x}{2}}[/tex]

[tex]y^{\prime\prime} = 49Ae^{-7x} + \frac{1}{4}Be^{-\frac{x}{2}}[/tex]

Now, we replace into the equation:

[tex]2y^{\prime\prime} - 13y^{\prime} - 7y = 0[/tex]

[tex]2(49Ae^{-7x} + \frac{1}{4}Be^{-\frac{x}{2}}) - 13(7Ae^{-7x} - \frac{1}{2}Be^{-\frac{x}{2}}) - 7(Ae^{7x} + Be^{-\frac{x}{2}}) = 0[/tex]

[tex]98Ae^{-7x} + \frac{1}{2}Be^{\frac{x}{2}} - 91Ae^{-7x} + \frac{13}{2}e^{-\frac{x}{2}} - 7Ae^{7x} - 7Be^{-\frac{x}{2}} = 0[/tex]

[tex]98Ae^{-7x} - 91Ae^{-7x} - 7Be^{-\frac{x}{2}} + \frac{1}{2}Be^{\frac{x}{2}}  + \frac{13}{2}e^{-\frac{x}{2}} - 7Be^{-\frac{x}{2}} = 0[/tex]

[tex]0A + 0B = 0[/tex]

[tex]0 = 0[/tex], thus, we found the identity, and for each constant A and B, the following is a solution.

--------------------------------------------------

Question b:

[tex]y = Ae^{7x} + Be^{-\frac{x}{2}}[/tex]

Since [tex]y(0) = 3[/tex]

[tex]A + B = 3 \rightarrow B = 3 - A[/tex]

--------------------------------------------------

[tex]y^{\prime} = 7Ae^{-7x} - \frac{1}{2}Be^{-\frac{x}{2}}[/tex]

Since [tex]y^{\prime}(0) = -5[/tex]

[tex]7A - \frac{1}{2}B = -5[/tex]

Using [tex]B = 3 - A[/tex]

[tex]7A - \frac{3}{2} + \frac{A}{2} = -5[/tex]

[tex]\frac{14A}{2} + \frac{A}{2} = -\frac{10}{2} + \frac{3}{2}[/tex]

[tex]\frac{15A}{2} = -\frac{7}{2}[/tex]

[tex]15A = -7[/tex]

[tex]A = -\frac{7}{15}[/tex]

--------------------------------------------------

Then, B is given by:

[tex]B = 3 - A = 3 - (-\frac{7}{15}) = \frac{45}{15} + \frac{7}{15} = \frac{52}{15}[/tex]

Thus, the values are: [tex]A = -\frac{7}{15}, B = \frac{52}{15}[/tex]

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Related Questions

evaluate -7x^2 -5 + y^2- forx = -2, y=4

Answers

Answer:

The (y^2 ) or (y^–2) It is not clear, I solved it in both ways (y^2) and (y^-2) .^_^

[tex] - 7 {x }^{2} - 5 + {y}^{2} \\ - 7( { - 2}^{2} ) - 5 + {4}^{2} \\ - 7( - 4) - 5 + 16 \\ 28 - 5 + 16 \\ = 39[/tex]

_______o_____o_______

[tex] - 7 {x }^{2} - 5 + {y}^{ - 2} \\ - 7( { - 2}^{2} ) - 5 + {4}^{ - 2} \\ - 7( - 4) - 5 + \frac{1}{16} \\ 28 - 5 + \frac{1}{16} \\ = 23.06[/tex]

I hope I helped you^_^

Assume the population of regulation basketball weights are normally distributed with a mean of 22 and a standard deviation of 1 ounce. If a sample of 100 regulation basketballs is taken, what is the probability that its sample mean will be greater than 22.2 ounces

Answers

Answer: 0.0228

Step-by-step explanation:

please check photo explanation

The probability that the sample mean will be greater than 22.2 ounces will be equal to 0.0228

What is probability?

Probability is calculated as the proportion of favorable events to all potential scenarios of an event. The proportion of positive results, or x, for an experiment with 'n' outcomes can be expressed.

As per the given values in the question,

[tex]\mu_x[/tex] = 22

σ(x) = σ/√n

= 1/√100

σ(x) = 0.1

P(x>22.2) = 1- P(x<22.2)

= 1- P(x × μ(x))/ σ(x) < (22.2 - 22)/0.1

1 - P (z < 2.00)

1- 0.9772

= 0.0228

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give ABCD is a trapizod , Ab = 13, CD= 14, BC = 15, and AD = 20 what is the area

Answers

Step-by-step explanation:

A=140sq. units

Step-by-step explanation:

ABCD

A=13

B=15

C=14

D=20

C=14×14

=196sqr.units

I need to find the distance B in the special counter sink shown

Answers

Answer:

Step-by-step explanation:

87°32' = 86°92'

(86°92')/2 = 43°46'

B = 13/(16cos(43°46')) = 1.125

Answer:

Step-by-step explanation:

Read image for instructions

Answers

The last part answers the first part for you, just look at the y-values.

In other words:

A' (-8, 2)

B' (-4, 3)

C' (-2, 8)

D' (-10, 6)

Explanation:

When you reflect any point over the x-axis, the y-value of the ordered pair is going to change.

This makes sense especially considering that the x-axis is horizontal, so the only way you could cross is to move up or down. If you were to move left or right, you'd only be able to cross the y-axis, since it's vertical.

Now for the last part, as I mentioned above, if you are reflecting across the y-axis, the x-values of the ordered pair is going to change.

A'' (8, 2)

B'' (4, 3)

C'' (2, 8)

D'' (10, 6)

Take note that the only thing that changes for the respective value is its sign, while the number itself stays the same.

determine whether the lines are parallel or not with proper reasons.​

Answers

Answer:

Parallel

Step-by-step explanation:

Because of interior alternate angles

Angle ARS and Angle BRS are Interior alternate angles in this case ..

The probability that a graduate of the Faculty of Finance will defend the diploma “excellent” is 0.6. The probability that he will defend his diploma “perfectly” and receive an invitation to work at the bank is 0.4. Suppose a student defends a diploma. Find the probability that he will receive an invitation to work in a bank?

Answers

The probability that he receives an invitation to work in a bank given that he defends his diploma excellently is [tex]\mathbf{0. \overline 6}[/tex]

The reason for the above probability value is as follows;

The known parameters are;

The probability that a graduate of the Faculty of Finance will defend the diploma excellently, P(A) = 0.6

The probability that he will defend perfectly and receive an invitation to work at a bank, P(A∩B) = 0.4

The unknown parameter is;

The probability that the student will receive an invitation from the bank given that the student defend the diploma excellent, [tex]\mathbf {P(B \ | \ A)}[/tex]

The process;

[tex]\mathbf{ P(B \ | \ A)}[/tex] is found using the conditional probability formula as follows;

[tex]\mathbf {P(B \ | \ A) = \dfrac{P(A \cap B) }{P(A)}}[/tex]

Plugging in the values, we get;

[tex]P(B \ | \ A) = \dfrac{0.4 }{0.6} = \dfrac{2}{3} = 0. \overline 6[/tex]

The probability that the student will receive an invitation from the bank given that the student defend the diploma excellent, [tex]P(B \ | \ A)[/tex] = [tex]\mathbf {0. \overline 6}[/tex]

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Convert 4.206 m into mm

Answers

Answer:

4206 is the answer of this question

Answer:

I think it will help you a lot.

Janet invests a sum of EUR in an account that offers 3.5% simple interest. After ten years her investment is worth 7425 EUR. How much did she invest?

Answers

We need to find the amount of money Janet invested in 10 years to yield 7425 EUR

She invested EUR 21,214.29

Simple interest = P × R × T

Where,

P = principal = ?

R = interest rate = 3.5% = 0.035

T = Time = 10 years

Simple interest = 7425 EUR

Simple interest = P × R × T

7425 = p × 0.035 × 10

7425 = p × 0.35

7425 = 0.35p

Divide both sides by 0.35

P = 7425 / 0.35

= 21,214.285714285

Approximately,

P = EUR 21,214.29

https://brainly.com/question/10936433

I will mark as brainliest:)

Answers

Answer:

Cube C

Step-by-step explanation:

[tex]{ \sf{because \: it \: is \: identical}}[/tex]

Click on the picture for the answer

Answers

Answer:

the answer is 1/14

hope this helps you

9514 1404 393

Answer:

  (a)  1/14

Step-by-step explanation:

Fractions are multiplied by multiplying numerators and denominators. They are reduced by cancelling common factors. When a product has an even number of minus signs, it is positive.

  [tex]\left(-\dfrac{3}{7}\right)\cdot\left(-\dfrac{1}{6}\right)=\dfrac{(-3)(-1)}{7\cdot6}=\dfrac{3}{7\cdot2\cdot3}=\dfrac{1}{7\cdot2}=\boxed{\dfrac{1}{14}}[/tex]

A(3, 7), B(5, 7), C(3-7), D(5, -7)
what is the area ?

Answers

Answer:

28 square units.

Step-by-step explanation:

This is a rectangle with sides (7 - (-7) and (5 - 3)

= 14 by 2

= 28 unit^2.

Dividing integers
7. (-154) ➗ (-14) =
11. (-40) ➗10=
15. 90 ➗ (-15)=
16. 108 ➗ (-9)=
17. (-48) ➗ (-6)=
18. (-105) ➗ 7=

Answers

first we shall learn the rules.when numbers with same sign are divided it gives pisitive sign but, when numbers of different signs are divided it gives negetive sign.

here,

7. (-154) ➗ (-14) =11

11. (-40) ➗10=-4

15. 90 ➗ (-15)=-6

16. 108 ➗ (-9)=-12

17. (-48) ➗ (-6)=8

18. (-105) ➗ 7=-15

hope it helps you..........

The number of bacteria in a certain culture grows exponentially at a rate of 1% per hour. Assuming that 5,000 bacteria are present initially, find the time required for the bacteria population to reach 45,000. (Round your answer to the nearest hour.)

Answers

9514 1404 393

Answer:

  221 hours

Step-by-step explanation:

The population is given by the exponential equation ...

  population = (initial value) × (1 +growth rate)^t

where the units of t are the same as the units of growth rate.

This lets us write ...

  p(t) = 5000×1.01^t

We want this to be 45000, so ...

  45000 = 5000×1.01^t

  9 = 1.01^t . . . . . . . . . . . . divide by 5000

  log(9) = t×log(1.01) . . . . take logs

  t = log(9)/log(1.01) ≈ 220.8

It will take about 221 hours for the population to reach 45000.


Differentiate 4x^2+y^2=36 with respect to x. Hence find the turning points of the curve.

Answers

If y = y(x), then the derivative with respect to x is dy/dx. Differentiating both sides of the given equation gives

d/dx [4x ² + y ²] = d/dx [36]

8x + 2y dy/dx = 0

2y dy/dx = -8x

dy/dx = -4x/y

The turning points of the curve, taken as a function of x, are those points where the derivative vanishes.

-4x/y = 0   ===>   x = 0

This value of x corresponds to two points on the curve,

4×0² + y ² = 36   ===>   y ² = 36   ===>   y = ±6

So there are two turning points, (0, -6) and (0, 6).

9(5x + 1) ÷ 3y

From the expression above, provide an example of each of the following: sum, term, product, factor, quotient, and coefficient. If any are not present, write "not present." (ill give brainiest and if there is any troll answers I will report and take this down )

Answers

Answer

3y(5x+1)

Step-by-step explanation:

9*(5x+1)/3y

3(5x+1)y

Answer:

Step-by-step explanation:

sum: 5x + 1

factor: 3 which divides into 9 evenly

quotient: the answer to division: 9(5x + 1)/(3y) = 3(5x +1)/y

coefficent: this depends on what you have been told. In my day, there were two kinds of coefficents

numerical: 5 and 3

literal: x and y

Business/multivariable calc question
help needed asap!!!!

Answers

Answer:

There is a   min     value of   376     located at (x,y) =   (9,7)  

============================================================

Explanation:

Solve the second equation for y

x+y = 16

y = 16-x

Then plug it into the first equation

f(x,y) = 3x^2+4y^2 - xy

g(x) = 3x^2+4(16-x)^2 - x(16-x)

g(x) = 3x^2+4(256 - 32x + x^2) - 16x + x^2

g(x) = 3x^2+1024 - 128x + 4x^2 - 16x + x^2

g(x) = 8x^2-144x+1024

The positive leading coefficient 8 tells us we have a parabola that opens upward, and produces a minimum value (aka lowest point) at the vertex.

Let's compute the derivative and set it equal to zero to solve for x.

g(x) = 8x^2-144x+1024

g ' (x) = 16x-144

16x-144 = 0

16x = 144

x = 144/16

x = 9

The min value occurs when x = 9. Let's find its paired y value.

y = 16-x

y = 16-9

y = 7

The min value occurs at (x,y) = (9,7)

Lastly, let's find the actual min value of f(x,y).

f(x,y) = 3x^2+4y^2 - xy

f(9,7) = 3(9)^2+4(7)^2 - 9*7

f(9,7) = 376

The smallest f(x,y) value is 376.

Find f(-1) given f(x) = –2x^3 + 3x^2 – 22

Answers

[tex]\\ \sf\longmapsto f(-1)[/tex]

[tex]\\ \sf\longmapsto -2x^3+3x^2-22[/tex]

[tex]\\ \sf\longmapsto -2(-1)^3+3(-1)^2-22[/tex]

[tex]\\ \sf\longmapsto -2(-1)+3(1)-22[/tex]

[tex]\\ \sf\longmapsto 2+3-22[/tex]

[tex]\\ \sf\longmapsto 5-22[/tex]

[tex]\\ \sf\longmapsto -17[/tex]

What is log10^6, considering log10^2=a and log10^3=b?

Answers

The answer is simply just a+b.

Solution:

log10^6=log10^2+log10^3

Since log10^2=a and log10^3=b,

The answer is a+b.

I think that the answer is a+b.

Simplify i^38 ????????

Answers

Answer:

i is defined as the square root of -1.

i^2 = -1

i^3 = -i

i^4 = 1

Following the pattern, we see that i^40 = 1, so i^38 is two above, or equal to -1.

So, i^38 = -1.

Let me know if this helps!

construct a rectangle PQRS, In which AB= 8cm and diagonal AC= 10cm​

Answers

A rectangle can be constructed using a straightedge, and a setsquare or compass

Please find attached the drawing of rectangle ABCD

The steps to construct the rectangle ABCD are as follows:

Question:

The missing part of the question is the name of the rectangle = ABCD

The given parameters are;

The length of the side AB = 8 cm

The length of the diagonal of the rectangle ABCD = AC = 10 cm

The steps to construct a rectangle are;

Draw the segment [tex]\overline{AB}[/tex] = 8 cm on a planeDraw perpendicular lines at points A and B with length h given by Pythagoras's theorem as follows

h² = [tex]\overline{AC}[/tex]² - [tex]\overline{AB}[/tex]²

∴ h² = 10² - 8² = 36

h = √36 = 6

h = 6 cm = The length of the sides [tex]\mathbf{\overline{AD}}[/tex] and [tex]\mathbf{\overline{CB}}[/tex]

Draw arcs with radius 6 cm from points A and B to intersect the perpendicular lines drawn from points A and B on the same side of the line [tex]\overline{AB}[/tex] at points D and CJoint point C to D with a straight line which is segment  [tex]\overline{CD}[/tex] and which completes the rectangle ABCD

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find coordinate of a point on x axis which is at a distance of 5 units from (5,4)​

Answers

Step-by-step explanation:

Hi there!

Please see attached picture for your answer.

Hope it helps!

0.18 divided by 0.04

Answers

If you plug that into a calculator you get 4.5
0.45 is just a normal division

Suppose that the manufacturer of a gas clothes dryer has found that, when the unit price is p dollars, the revenue R (in dollars) is R(P) = - 8p^2 + 24,000p. What unit
price should be established for the dryer to maximize revenue? What is the maximum revenue?
The unit price that should be established to maximize revenue is $|
(Simplify your answer.)

Answers

Here we have a problem of maximization and quadratic equations.

The unit prize that maximizes the revenue is $1,500, and the maximum revenue is $18,000.

We know that the revenue equation is:

R(P) = - 8p^2 + 24,000p

Where the variable p is the price.

Now we want to find the value of p that maximizes the revenue.

To do it, we can see that the revenue equation is a quadratic equation with a negative leading coefficient.

This means that the arms of the graph will go downwards, then the maximum point of the graph will be at the vertex.

Remember that for an equation like:

y = a*x^2 + b*x+ c

The x-value of the vertex is at:

x = -b/(2*a)

Then for the equation:

R(P) = - 8p^2 + 24,000p

The vertex is at:

p = -(24,000)/(2*-8) = 1,500

The value of p that maximizes the revenue is p = $1,500

To get the maximum revenue, we need to evaluate the revenue equation in that p value.

R(1,500) =  - 8*(1,500)^2 + 24,000*1,500 = 18,000

And the revenue equation is in dollars, then the maximum revenue is 18,000 dollars.

If you want to learn more, you can read:

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p = 1500  $    the unit price

R(p) = 18000000 $ maximum revenue

We will use two different procedures to calculate the maximum revenue.

That is equivalent to solve the problem and after that to test the solution

The first one is:

R(p) = - 8*p² + 24000*p

we realize that R(p) is a quadratic function ( a parabola) of the form:

y = a*x² + b*x + c    ( c = 0 in this case)

We also know that  as the coefficient of p² is negative the parabola opens downwards then the vertex is a maximum value for R(p), and the x coordinate of p is:

x = p =  - b/2*a   then by substitution

p = - ( 24000)/ 2 ( - 8)

p = 1500  $   and for that value of p

R(p) = - 8 ( 1500)² + 24000* (1500)  = - 18000000 + 36000000

R(p) = 18000000 $

The second procedure is solving with the help of derivatives.

R(p) =  - 8*p² + 24000*p

Tacking derivatives on both sides of the equation we get:

R´(p) = -16p  +  24000

If R´(p) = 0    then    -16p  +  24000 = 0

p = 24000/ 16         p  =  1500

if we check for the second derivative

R´´(p) = -16          -16 < 0  therefore there is a maximum value for R(p) when p = 1500, and that value is:

By substitution in R(p)

R(p) = -8 *(1500)² + 24000* 1500

R(p) =  - 18000000 + 36000000

R(p) = 18000000 $

Using the formula D = s:t where D equals distance traveled, r equals the average rate of
speed, and t equals the time traveled, choose the expression or equation that correctly
represents this information.
Mary drove 150 miles in three hours. What was her average rate of speed?
=
150 = 3
r = 3 = 150
O p + 150 · 3

Answers

Answer: r = 50 miles/h

Step-by-step explanation:

Let r be the rate of average speed.

Then

r = D/t

r = 150/3

r = 50 miles/h

please click thanks and mark brainliest if you like :)

plzzz help me i need help picture below
A local bakery buys their flour in bulk. The relationship between the cost of the flour and its weight is shown in the graph below.



Is the relationship shown a direct variation? Explain your reasoning using complete sentences.
The point (1, 0.50) is on this graph. What does this ordered pair represent?
Approximately how much does the bakery pay for 40 pounds of flour?

Answers

Answer:

It is a direct variation...

The price of flour does not increase or decrease the

more that you purchase (no discount for large purchases)

(1,0.5) means that a pound of flour costs 50

40 pounds would cost $20

Step-by-step explanation:

what is the inverse of y=3x+3?

Answers

Answer:

The inverse is x/3 -1

Step-by-step explanation:

y = 3x+3

To find the inverse, exchange x and y

x = 3y+3

Solve for y

x-3 =3y+3-3

x-3 = 3y

Divide by 3

x/3 - 3/3 = 3y/3

x/3 -1 = y

The inverse is x/3 -1

Armando's carpet has an area of 220 square feet. He hires the Carpet Pro carpet cleaning service, which is able to clean 9 square feet of his carpet every minute. Therefore, in the first minute, CarpetPro is able to clean 9 square feet of Armando's carpet (leaving 211 square feet remaining to be cleaned). In the second minute, the cleaner is again able to clean 9 square feet of carpet (leaving 202 square feet to be cleaned), etc. Which of the following functions expresses the number of square feet that still remain to be cleaned after t minutes from the time that the carpet cleaner began cleaning this carpet.
a. A(t) = 220 - 9
b. A(t) = 220 - 0.1
c. A(t) = 220(0.1)
d. A(t) = 220(0.96)
e. A(t) 220 - 0.96

Answers

Answer:

The answer is A

Step-by-step explanation:

The answer needs to be in slope-intercept form or y=mx+b because the amount of carpet being cleaned every minute is a constant decrease of 9 square feet.

So our b value (or how much carpet cleaned at 0 minutes) is 220

And our m value (or slope or how much carpet is being cleaned every minute) is 9

So if we plug the variables with the tangible numbers we get A(t) = -9x+220 or A(t) = 220-9x.

provided by gauth math

Taylor wants to find the perimeter of a rectangular playground. The lenght of the playground measures (3x-20) metres. The width of the playground measures (2x+4) metres. What is the perimeter of the playground? ​

Answers

Answer:

Step-by-step explanation:

P = 2(3x-20) + 2(2x+4) = (6x-40) + (4x+8) = 10x-32

The required perimeter of the playground is 10x-32.

The length of the playground measures (3x-20) metres.
The width of the playground measures (2x+4) metres.

What is the perimeter?

Perimeter, is the measure of the figure on its circumference.

The Required perimeter is for the playground is given by
= 2(3x-20) + 2(2x+4)

= 10x-32

Thus the required perimeter of the playground is 10x-32.

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May I get some help with this question?

Answers

bisector perpendicular is a line perpendicular to the segment and passes through the midpoint of the segment. S is midpoint of the segment.
hence
XS=ZS
third choice
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