d[(x^3-1)^4/x^3] / dx = [x^3 * d[(x^3-1)^4]/dx - (x^3-1)^4 * d(x^3)/dx] / x^6 =
= [x^3 * 4(x^3-1)^3 * 3*x^2 - (x^3-1)^4 * 3*x^2] / x^6 = 3*(x^3-1)^3 * [x^3 * 4 - (x^3-1)] / x^4 =
= 3*(x^3-1)^3*[3*x^3+1] / x^4
d[(x^3-1)^4/x^3] / dx = [x^3 * d[(x^3-1)^4]/dx - (x^3-1)^4 * d(x^3)/dx] / x^6 =
= [x^3 * 4(x^3-1)^3 * 3*x^2 - (x^3-1)^4 * 3*x^2] / x^6 = 3*(x^3-1)^3 * [x^3 * 4 - (x^3-1)] / x^4 =
= 3*(x^3-1)^3*[3*x^3+1] / x^4