I'm not understanding what to do to the first problem after I cancel out the cscx in the top and bottom. The 2nd and 3rd problems are still kind of confusing.

1) Int (cscx cotx)/((csc(x))^5) dx

2) Int (dx)/(sqrt(1-16x^2)

3) Int ((x^3)-(3x^2)+3x)/(x-1) dx