Question involving the shell method

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Homework Statement


Use the method of cylindrical shells to find the volume generated by rotating the region bounded by the given curves about the given axis:

y = x2, y = 0, x = 1, x = 2, about x = 1

Homework Equations



V = 2\pi\intxf(x)

The Attempt at a Solution



I am assuming based off the graph that my f(x) would be equal to 4-x2, but I am having difficulty figuring out the respective x value. Any help?
 
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Then I suggest you look at your graph again! Each shell, at a specific x, has a length ranging from y= 0 to y= x^2 so that its height is x^2- 0= x^2.
 
Wow... that was silly of me. That makes a lot more sense. So I would integrate 2\pi\int(x-1)(x2)dx from 1 to 2, which gives me an answer of 17/2. Thanks for the help.
 
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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