The difference quotient of -x^3

can u give me the steps and the answer? Thanks ^^

[f(x + h) - f(x)] / h

[-(x + h)^3 - (-x^3)] / h


f(x + h) = -(x + h)^3 = -(x^3 + 3x^2*h + 3x*h^2 + h^3) = -x^3 - 3x^2*h - 3x*h^2 - h^3

[f(x + h) - f(x)] = (-x^3 - 3x^2*h - 3x*h^2 - h^3) + x^3 = - 3x^2*h - 3x*h^2 - h^3

[f(x + h) - f(x)] / h = (- 3x^2*h - 3x*h^2 - h^3) / h = - 3x^2 - 3x*h - h^2