x(x-1)+y(y+1)-2xy
还有一题
(x+y)(x+y+2xy)+(xy+1)(xy-1)
x(x-1)+y(y+1)-2xy
还有一题
(x+y)(x+y+2xy)+(xy+1)(xy-1)
X(X-1)+Y(Y-1)-2XY=X平方-X+Y平方+Y-2XY等于(X-Y)平方-(X-Y)
最后结果就是(X-Y)(X-Y+1)
第二题:待会
x(x-1)+y(y+1)-2xy=x^2-x+y^2+y-2xy
=(x^2+y^2-2xy)-(x-y)
=(x-y)^2-(x-y)
=(x-y)(x-y-1)
(x+y)(x+y+2xy)+(xy+1)(xy-1)=(x+y)[(x+y)+2xy]+(xy)^2-1
=(x+y)^2+2(xy)(x+y)+(xy)^2-1
=[(x+y)+xy]^2-1
=[(x+y)+xy+1][(x+y)+xy-1]
=(x+y+xy+1)(x+y+xy-1)
x(x-1)+y(y+1)-2xy=x的平方-x+y的平方-2xy=(x-y)的平方-(x-y)=(x-y)(x-y-1)
(x+y)(x+y+2xy)+(xy+1)(xy-1)=(x+y)的平方+2(x+y)xy+x的平方*y的平方-1
=(x+y+xy)的平方-1
=(x+y+xy-1)(x+y+xy+1)
(x-y)(x-y-1)
x(x-1)+y(y+1)-2xy
=x^2-x+y^2+y-2xy
=(x-y)^2-(x-y)
=(x-y)(x-y-1)
x(x-1)+y(y+1)-2xy
=x^2-x+y^2+y-2xy
=(x^2-2xy+y^2)-(x-y) =(x-y)^2-(x-y)
=(x-y)(x-y-1)