1.
X - (y1(X)/y2(X)) --> X
Disp X

where y1 = f and y2 = f'.

2.
-1.518512, when we approximate the zero to six decimal places.

3.
0.508499 and 1.243596, when we approximate the zeros to six decimal places.

4.
((4/5)^(1/4), + ∞).

5.
(- ∞, -(4/5)^(1/4)) for the zero -1.518512.
(-0.683, 0.905) for the zero 0.508499.

6.
± (4/5)^(1/4), since the derivative at these two x-values is zero.