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Pachacha [2.7K]
2 years ago
11

Is this correct and if not which one is right

Mathematics
2 answers:
aivan3 [116]2 years ago
5 0
Yes- answer D 3^x + 15x-3 is the right answer!
just olya [345]2 years ago
3 0
Yes it's correct..........
You might be interested in
Consider the following. (A computer algebra system is recommended.) y'' + 3y' = 2t4 + t2e−3t + sin 3t (a) Determine a suitable f
drek231 [11]

First look for the fundamental solutions by solving the homogeneous version of the ODE:

y''+3y'=0

The characteristic equation is

r^2+3r=r(r+3)=0

with roots r=0 and r=-3, giving the two solutions C_1 and C_2e^{-3t}.

For the non-homogeneous version, you can exploit the superposition principle and consider one term from the right side at a time.

y''+3y'=2t^4

Assume the ansatz solution,

{y_p}=at^5+bt^4+ct^3+dt^2+et

\implies {y_p}'=5at^4+4bt^3+3ct^2+2dt+e

\implies {y_p}''=20at^3+12bt^2+6ct+2d

(You could include a constant term <em>f</em> here, but it would get absorbed by the first solution C_1 anyway.)

Substitute these into the ODE:

(20at^3+12bt^2+6ct+2d)+3(5at^4+4bt^3+3ct^2+2dt+e)=2t^4

15at^4+(20a+12b)t^3+(12b+9c)t^2+(6c+6d)t+(2d+e)=2t^4

\implies\begin{cases}15a=2\\20a+12b=0\\12b+9c=0\\6c+6d=0\\2d+e=0\end{cases}\implies a=\dfrac2{15},b=-\dfrac29,c=\dfrac8{27},d=-\dfrac8{27},e=\dfrac{16}{81}

y''+3y'=t^2e^{-3t}

e^{-3t} is already accounted for, so assume an ansatz of the form

y_p=(at^3+bt^2+ct)e^{-3t}

\implies {y_p}'=(-3at^3+(3a-3b)t^2+(2b-3c)t+c)e^{-3t}

\implies {y_p}''=(9at^3+(9b-18a)t^2+(9c-12b+6a)t+2b-6c)e^{-3t}

Substitute into the ODE:

(9at^3+(9b-18a)t^2+(9c-12b+6a)t+2b-6c)e^{-3t}+3(-3at^3+(3a-3b)t^2+(2b-3c)t+c)e^{-3t}=t^2e^{-3t}

9at^3+(9b-18a)t^2+(9c-12b+6a)t+2b-6c-9at^3+(9a-9b)t^2+(6b-9c)t+3c=t^2

-9at^2+(6a-6b)t+2b-3c=t^2

\implies\begin{cases}-9a=1\\6a-6b=0\\2b-3c=0\end{cases}\implies a=-\dfrac19,b=-\dfrac19,c=-\dfrac2{27}

y''+3y'=\sin(3t)

Assume an ansatz solution

y_p=a\sin(3t)+b\cos(3t)

\implies {y_p}'=3a\cos(3t)-3b\sin(3t)

\implies {y_p}''=-9a\sin(3t)-9b\cos(3t)

Substitute into the ODE:

(-9a\sin(3t)-9b\cos(3t))+3(3a\cos(3t)-3b\sin(3t))=\sin(3t)

(-9a-9b)\sin(3t)+(9a-9b)\cos(3t)=\sin(3t)

\implies\begin{cases}-9a-9b=1\\9a-9b=0\end{cases}\implies a=-\dfrac1{18},b=-\dfrac1{18}

So, the general solution of the original ODE is

y(t)=\dfrac{54t^5 - 90t^4 + 120t^3 - 120t^2 + 80t}{405}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,-\dfrac{3t^3+3t^2+2t}{27}e^{-3t}-\dfrac{\sin(3t)+\cos(3t)}{18}

3 0
3 years ago
Mai drove to the mountains last weekend. There was heavy traffic on the way there, and the trip took 8 hours. When Mai drove hom
Vesna [10]

Answer:

Mai lives 384 miles away from the mountains

Step-by-step explanation:

Let d represent distance between Mai's house and mountains and r represent Mai's rate while going to mountains.

We have been given that there was heavy traffic on the way there, and the trip to mountains took 8 hours.

\text{Distance}}=\text{Time}\times \text{Speed}

d=8r...(1)

We are also told that when Mai drove home, there was no traffic and the trip only took 6 hours. Her average rate was 16 miles per hour faster on the trip home.

d=6(r+16)...(2)

Upon equating equation (1) and equation (2), we will get:

8r=6(r+16)

8r=6r+96

8r-6r=6r-6r+96

2r=96

\frac{2r}{2}=\frac{96}{2}

r=48

Upon substituting r=48 in equation (1), we will get:

d=8r\Rightarrow 8(48)=384

Therefore, Mai lives 384 miles away from the mountains.

8 0
2 years ago
Please guys i really need your help and please explain how you got it please
lina2011 [118]
The answer would be C because in order to find the area of a figure, you would need to multiply its height by its width. finding the area of a figure is the same as finding how many units are in a figure. because this is a square and all the sides are equal, by counting the total number of units, you can find the area.
5 0
3 years ago
Math help please I promise to give brainliest
AlekseyPX

Answer:

y = 0.5

x = 4 - y (0.5)

3.5 = 4 - 0.5

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

3x - 10 = y

3(3.5) - 10 = y

10.5 - 10 = y

0.5 = y

5 0
3 years ago
Read 2 more answers
A short-order cook can prepare 40 hamburgers in 30 minutes. The cook calculates a unit rate of 60 hamburgers per hour. She multi
Rus_ich [418]

Answer:

B is correct answer mark as brainliest answer

3 0
3 years ago
Read 2 more answers
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