x-y/7 - x+y/10 =1/2

{ x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3 若7x+10y分之5x+y=1/2,则x/y= 1、x(x-y)(x+y)-x(x+y)^2 先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y x+y=3 x+2y=9 3/x+1=y y-x=3 y=2x-3 y-3x=1 2(x+1)-y=6 7x-5y=-9 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值 7x-3y/5=5x-y/3-x+y/2 x-1/5=y+1/3 解方程组:(x+3)(y-2)=(x-3)(y+10),(x+1)(y+3)=(x-2)(y+12) 2(x+y)-3(x-y)=1 6(x+y)+7(x-y)=51 解方程组 2(x+y)-3(x-y) =1 6(x+y)+7(x-y)=51大神们帮帮忙 解方程组﹛2(x+y)-3(x-y)=1 6(x+y)+7(x-y)=51 10/x+y+3/x-y=-5 15/x+y-2/x-y=-1（用换元法解此方程组）