plug this formula into the graphing calculator:
(NOTE - this formula can be used with any Newton's method problem when needing to find roots: x-(original fx/derivative of fx)
From the graphing screen, hit 2nd + Trace, select Value, put x=-1. The y-value given on the screen is the "new" x-value. Now do 2nd + Trace again this time typing in the "new" x-value, the new given y-value is the next "new" x-value. Keep doing this over and over until the y-values stop growing/shrinking.