（x2+5x+3)(x2+5-2)-6,(x-1)(x+2)(x-3)(x+4)+24,3x2-2(2a+1)x+a2-1,a2x+b2+(1-x) -(a+b)2x(1-x)-4b
问题描述：
（x2+5x+3)(x2+5-2)-6,(x-1)(x+2)(x-3)(x+4)+24,3x2-2(2a+1)x+a2-1,a2x+b2+(1-x) -(a+b)2x(1-x)-4b
(a2-a)x2-(ab+2b)x-6b2 用十字相乘法解决
答
（x2+5x+3)(x2+5x-2)-6
=(x²+5x)²+(x²+5x)-12
=(x²+5x+4)(x²+5x-3)
=(x+4)(x+1)(x²+5x-3)
(x-1)(x+2)(x-3)(x+4)+24
=(x²+x-2)(x²+x-12)+24
=(x²+x)²-14(x²+x)+48
=(x²+x-6)(x²+x-8)
=(x+3)(x-2)(x²+x-8)
3x2-2(2a+1)x+a2-1
=3x²-(4a+2)x+(a+1)(a-1)
=(3x-a+1)(x-a-1)
a2x+b2+(1-x) -(a+b)2x(1-x)-4b
(a2-a)x2-(ab+2b)x-6b2
=a(a-1)x²-(ab+2b)x-6b²
=(ax+2b)(ax-x-3b)