解一下方程：x=2y-1:；x+3y=6 x-9.8y=2.6:；1/3x-3y=1

{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 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 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 ｛4/(x+y)+6/(x-y)=3 ｛9/(x-y)-1/(x+y)=1 2(x+y) 3x+3y=24 x+y/2x x y/2y= 1 解方程：x-x-1/2=2-x+2/3 y+6=y+2/2-y-5/3 解方程：3x+2y/4=2x+y/5=x-y+1/6要详细过程 解方程组：2(x-y)/3-x+y/4=-1 ,6(x+y)-4(2x-y)=16 2(x+y)-3(x-y)=1 6(x+y)+7(x-y)=51 解方程组 解二元一次方程组{3(x+y)-(x-y)=4,x+y/2+x-y/6=1 解方程组﹛2(x+y)-3(x-y)=1 6(x+y)+7(x-y)=51 解二元一次方程组{3(x+y)-4(x-y)=4,x+y/2+x-y/6=1