(3x²)³-7x³【x³-x(4x²+1)】+(-x²)²=3x^6-7x³(x³-4x³-x)+x⁴=3x^6-7x³(-3x³-x)+x⁴=3x^6+21x^6+7x⁴+x⁴=24x^6+8x⁴