Given y=1/5x^5+4x^3+36x-1000, what starting points would make Newton's method f…

Given y=15x5+4x3+36x1000y=\frac{1}{5}x^5+4x^3+36x-1000, what starting points would make Newton's method fail? Find a formula for the iterate xn+1x_{n+1} in term of xnx_n.
More Newton's Method Questions: