先化简,再求值x/x的平方-2xy+y平方×(x-y)+(2x+2/x-y-2),其中x,y满足方程组x+2y=3,x-y=-5.
问题描述：
先化简,再求值x/x的平方-2xy+y平方×(x-y)+(2x+2/x-y-2),其中x,y满足方程组x+2y=3,x-y=-5.
答
原式=x/(x-y)²×(x-y)+(2x+2-2x+2y)/(x-y)
=x/(x-y)+(2+2y)/(x-y)
=(x+2y+2)/(x-y)
=(3+2)/(-5)
=-1
答
x/x的平方-2xy+y平方×(x-y)+(2x+2/x-y-2)
=x/(x-y)²×(x-y)+(2x+2/x-y-2)
=x/(x-y)+(2x+2)/(x-y)-2
=(3x+2)/(x-y)-2
=(x+2y+2)/(x-y)
=(3+2)/(-5)
=-1