当2x-y\x+y=3时,求代数式2x-y/2x+2y+x+y/6x-3y的値.
问题描述：
当2x-y\x+y=3时,求代数式2x-y/2x+2y+x+y/6x-3y的値.
答
2x-y\x+y=3
2x-y=3(x+y)
2x-y=3x+3y
3x-2x=-y-3y
x=-4y
2x-y/2x+2y+x+y/6x-3y
=(-8y-y)/(-8y+2y)+(-4y+y)/(-24y-3y)
=3/2+1/9
=29/18