For each of the following functions, find the maximum and minimum values on the indicated intervals, by finding the points in the interva? where the derivative is $0,$ and comparing the values at these points with the values at the end points.
(i) $\quad f(x)=x^{3}-x^{2}-8 x+1$ on [-2,2]
(ii) $f(x)=x^{5}+x+1$ on [-1,1]
(iii) $f(x)=3 x^{4}-8 x^{3}+6 x^{2} \quad$ on $\left[-\frac{1}{2}, \frac{1}{2}\right]$
(iv) $f(x)=\frac{1}{x^{5}+x+1}$
on $\left[-\frac{1}{2}, 1\right]$
(v) $f(x)=\frac{x+1}{x^{2}+1}$ on $\left[-1, \frac{1}{2}\right]$
(vi) $f(x)=\frac{x}{x^{2}-1}$ on [0,5]