题目3y=7+x=2y-x+1y=2x=-1

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 分式加减的几道题目求速度1 .(x+y)²/（x-z)(y-z) - (y+z)²/（x-z)(y-z) = 2.2x+3y/x-y+2y/y-x-3y/x-y= 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 题目3y=7+x=2y-x+1y=2x=-1 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 解方程组题目一道(x+y)(x-2y)=-5(x-y)(x+2y)=7 x+2y=2x+y+1=7x-y 求：2x-y? (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 变量x,y满足约束条件,x+y>=3,x-y>=-1,2x-y (x-y)^2+(x+y)(x-y) 其中 X =3 Y=-1 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 方程组：第一题（5+1）x=5y 第二题x-y/3=x+y/2 4y-4x=30+10 2x-3y=7（5+1）x=5y x-y/3=x+y/2 4y-4x=30+10 2x-5y=7 上面那个题目错的 (x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一