括号3x三次方-2乘以括号X+4减括号x平方-3乘以括号3X-:5=(3x³-2)(x+4)-(x²-3)×(3x-5)=3x⁴-2x+12x³-8-3x³+9x+5x²-15=3x⁴+9x³+5x²+7x-23 9乘以括号x+2乘以括号x-2减括号3X-2的平方=9(x+2)(x-2)-(3x+2)²=9x²-36-9x²-12x-4=-12x-40
