turunan dari fx=(x²+2x)³

f'(x) = 3 (x²+2x)² (2x+2)
= 6 (x²+2x)² (x+1)

fx = (x²+2x)(x²+2x)(x²+2x)
fx = (2x⁴+4x³+4x²)(x²+2x)
fx = 2x^6 + 8x^5 + 12x⁴+8x³
fx` = 6.2x^5 + 5.8x⁴+4.12x³+3.8x²
fx` = 12x^5+40x⁴+48x³+18x²

koreksi ya kalo salah ;)