Answer:
Step-by-step explanation:
For this case we are interested on the region shaded on the figure attached.
And we can find the volume with the method of rings.
The area on this case is given by:
![A(x) = \pi [f(x)]^2 = \pi r^2 = \pi [3x]^2 = 9\pi x^2](https://tex.z-dn.net/?f=%20A%28x%29%20%3D%20%5Cpi%20%5Bf%28x%29%5D%5E2%20%3D%20%5Cpi%20r%5E2%20%3D%20%5Cpi%20%5B3x%5D%5E2%20%3D%209%5Cpi%20x%5E2)
And the volume is given by the following formula:

For our case our limits are x=0 and x=2 so we have this:

And if we solve the integral we got this:
![V= \pi [\frac{x^3}{3}]\Big|_0^{2}](https://tex.z-dn.net/?f=%20V%3D%20%5Cpi%20%5B%5Cfrac%7Bx%5E3%7D%7B3%7D%5D%5CBig%7C_0%5E%7B2%7D)
And after evaluate we got this:
![V=\pi [(\frac{8}{3} )-(\frac{0}{3} )]](https://tex.z-dn.net/?f=%20V%3D%5Cpi%20%5B%28%5Cfrac%7B8%7D%7B3%7D%20%29-%28%5Cfrac%7B0%7D%7B3%7D%20%29%5D)
When multiplying, you add indices
so it's 5^15
when dividing, you minus indices just fyi
Answer:
x=5
Step-by-step explanation:
20(20-x) = 300
Divide each side by 20
20/20(20-x) = 300/20
20-x = 15
Subtract 20 from each side
20-x-20 = 15-20
-x = -5
Multiply each side by -1
x = 5