expand the expression as a product of factors (x-t)3
(x-t)(x-t) = x^2 - 2xt + t^2(x^2 - 2xt + t^2)(x - t) = x^3 - 2x^2t + xt^2 - xt^2 + 2xt^2 - t^3 = x^3 - t^3 - 2x^2t + 2xt^2