Integration of 1/x^2 sqrt(16-x) with substitution

teng125
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my question is integra 1 / x^2 sqr root(16-x^2)
i use x = 4 sin y
then i got to integrate 1/16 times [1/(sin y)^2] in which i got stuck.pls help...how do i continue from there as i not sure ow to integra 1/(siny^2
 
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\frac{1}{sin^2y}= csc^2y- you should know the integral for that. What is the derivative of cot y?

(Sorry- I had left out a "}")
 
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Since I can't see Halls' Latex image, he was saying that \int \csc^2(y)dy is very simple, noting that what the derivative of cot(y) is.
 
Ivy's image is: \frac{1}{sin^2y}= csc^2y
 
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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