Use the washer method to find the volume of the solid generated when the region bounded by $y= 3x$ and $y=x^2$

Question

I have a quick question on my homework. I am not seeing why this is incorrect.

It states to the "Use the washer method to find the volume of the solid generated when the region bounded by $y= 3x$ and $y=x^2$ is revolved about the​ $x$-axis. What would be the Volume of the region?

The bounds are b. $2$ and a. $0$

I keep getting $54\pi$. Am I doing something incorrectly?

Answer 1

First of all your bounds are $a=0$ and $b=3.$

The integral is then $$ \int _0^3 \pi (9x^2-x^4) dx,$$

which is easy enough.