Question

(x²+2x-3)（x²+2x-24）+90的答案是多少？

要具体过程，因式分解，谢谢！

Answer 1

(x²+2x-3)(x²+2x-24)+90
=（x²+2x）²-27（x²+2x）+72+90
=（x²+2x）²-27（x²+2x）+162
=（x²+2x-9）（x²+2x-18）

Answer 2

(x²+2x-3)（x²+2x-24）+90
=(x+3)(x-1)(x+6)(x-4)+90

追问

因式分解结果一定要是乘积的形式

追答

=(x²+2x-3)[(x²+2x-3)-21]+90
=(x²+2x-3)²-21(x²+2x-3)+90
=[(x²+2x-3)-6][(x²+2x-3)-15]
=(x²+2x-9)(x²+2x-18)