分解因式用十字相乘(x-y)的平方+3(x的平方-y的平方)-4(x+y)的平方

11 |

(x-y)的平方+3(x的平方-y的平方)-4(x+y)的平方=[(x-y)+4(x+y)][(x-y)-(x+y)]=(5x+3y)(-2y)=-2y(5x+3y)...

千问 | 2013-7-4 10:14:25 | 显示全部楼层

(x-y)^2+3(x^2-y^2)-4(x+y)^2=x^2-2xy+y^2+3x^2-3y^2-4(x^2+2xy+y^2)=4x^2-2y^2-2xy-4x^2-8xy-4y^2=-(6y^2+10xy)...

千问 | 2013-7-4 10:14:25 | 显示全部楼层

(x-y)^2+3(x^2-y^2)-4(x+y)^2=(x-y)^2+3(x+y)(x-y)-4(x+y)^2=[(x-y)+4(x+y)][(x-y)-(x+y)]=-2y(5x+3y)...

千问 | 2013-7-4 10:14:25 | 显示全部楼层

（x-y）^2+3(x-y)(x+y)-4(x+y)^2=【(x-y)-(x+y)】【x-y+4（x+y）】=-2y(5x+3y)=-10xy-6y^2...

主题	0 回帖	4882万积分

Rank: 8 Rank: 8

热门排行