把(x2+3x+2)(x2-9x+20)-72分解因式，要详细过程

显示全部楼层 · 2013-5-4 23:09:22

(x2+3x+2)(x2-9x+20)-72=(x+1)(x+2)(x-4)(x-5)-72=(x+1)(x-4)(x+2)(x-5)-72=(x^2-3x-4)(x^2-3x-10)-72=(x^2-3x)^2-14(x^2-3x)+40-72=(x^2-3x)^2-14(x^2-3x)-32=(x^2-3x-16)(x^2-3x+2)=(^2-3x+16)(x-1)(x-2) 不懂可追问满意请采纳谢谢...

千问 · 2013-5-4 23:09:22

(x2+3x+2)(x2-9x+20)-72=(x+2)(x+1)(x-4)(x-5)-72=[(x+2)(x-5)][(x+1)(x-4)]-72=(x^2-3x-10)(x^2-3x-4)-72=(x^2-3x)^2-14(x^2-3x)+40-72=(x^2-3x)^2-14(x^2-3x)-32=(x^2-3x-16)(x^2...

千问 · 2013-5-4 23:09:22

解：(x2 + 3x + 2)(x2 - 9x + 20) -72
= (x + 1)(x +2)(x - 4)(x - 5) - 72
= (x + 1)(x - 4)(x + 2)(x - 5) - 72
= (x2 - 3x - 4)(x2 - 3x - 10) -...