Find an equation of the tangent line to the graph of the function f defined by the following equation at the indicated point.

(x - y - 1)3 = x; (1, -1)
y =

y+1 = -1/f'(1) (x-1)

3(x-y-1)^2 (1-y') = 1
at (1,-1)
-3(1-y') = 1
y' = 4/3