1.计算(x+2)/(x+1)-(x+3)/(x+2)-(x-4)/(x-3)+(x-5)/(x-4)2.解方程2x/(2x-1)+x/(x-2)=23.先化简再求值求(1/x²-1/y²)[(x²-xy+y²)/(x-y)+(x²+xy+y²)/(x+y)]的值,其中x=1/2y=1/4

　　1.计算

　　(x+2)/(x+1)-(x+3)/(x+2)-(x-4)/(x-3)+(x-5)/(x-4)

　　2.解方程

　　2x/(2x-1)+x/(x-2)=2

　　3.先化简再求值求(1/x²-1/y²)[(x²-xy+y²)/(x-y)+(x²+xy+y²)/(x+y)]的值,其中x=1/2y=1/4