Given the function f (x) = x ^ 3-x, find the tangent equation of the curve y = FX at x = t

Given the function f (x) = x ^ 3-x, find the tangent equation of the curve y = FX at x = t

The derivative of F (x) = x ^ 3-x is f '(x) = 3x ^ 2-1, and the tangent slope at x = t is k = 3T ^ 2-1
The function passes through the point (T, T ^ 3-T) and substituting y = KX + B to get b = - 2T ^ 3
So the required equation is y = (3T ^ 2-1) x-2t ^ 3