How do you find the volume of a solid of revolution using integration?

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Homework Statement



x=2y^2
x=0
y=+-6
rotated around y

Homework Equations


integral 2pi*x(f(x)dx

The Attempt at a Solution



integral from -6 to 6 of 2pi*y*2y^2 dy
but i get something far less than the correct answer
 
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What are all the * symbols supposed to mean? Multiplication?

Just think of this as Area times length. Since it's rotation around the y-axis you can see that it's easiest to differentiate with respect to y. It's going to make a bunch of little circles. What is the radius of those? (your function?).

From there, you need to plug it into the area of a circle to get pi(radius)^2
So if the volume of the solid is area times width, and in the integration dy is the width, what integral would solve this problem?
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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