初一因式分解题

显示全部楼层 · 2008-8-29 10:49:37

（x+1)(x+3)(x+5)（x+7)+15

x^2-2xy+y^2-13x+13y-30
6x^2-7xy-3y^2-x+7y-2
x^2+x-2
a^2-10ab+25b^2-5a+25b-6
x^2-4xy+3y^2-x-y-2
x^2+3x-(a^2+a-2)

千问 · 2008-8-29 10:49:37

1, (x+1)(x+3)(x+5)(x+7)+15 =[(x+1)(x+7)][(x+3)(x+5)]+15 =(x^2+8x+7)(x^2+8x+15)+15 =(x^2+8x+7)[(x^2+8x+7)+8]+15 =(x^2+8x+7)^2+8(x^2+8x+7)+15 =[(x^2+8x+7)+3][(x^2+8x+7)+5] =(x^2+8x+10)(x^2+8x+12) =(x^2+8x+10)(x+2)(x+6)2, x^2-2xy+y^2-13x+13y+30 =(x-y)^2-13(x-y)+30 =(x-y-3)(x-y-10) 3, 6X^2-7xy-3y^2-x+7y-2 ...

千问 · 2008-8-29 10:49:37

（x+1)(x+3)(x+5)（x+7)+15 =(x^2+8x+7)(x^2+8x+15)+15=(x^2+8x)^2+22(x^2+8x)+120=(x^2+8x+10)(x^2+8x+12)=(x^2+8x+10)(x+2)(x+6) x^2-2xy+y^2-13x+13y-30 =(x-y)^2-13(x-y)-30=...

千问 · 2008-8-29 10:49:37

2：（x-y-15)（x-y+2)4：（x-2)（x+1）5：（a-5b-6)(a-5b+1)7：x（x+3)-（a-1)（a+2)...