x+3y=9① 3(y-1)=2x②

① X+Y=3 Y=2X-3 ② x+2y=9 y-3x=1 ③3/x+1=y 2（x+1)=6 ④ y-x=3 7x- ①｛2X-5y=21,②｛2x+y=6,③｛x-3y=1,④｛y=-2x=3 ｛y=-x.｛y=1/2x+1.｛5x-9 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 9y=3x-(x-1),4(x+y)-(2x+4)=8y (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 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 下列函数：①y=-3x②y=2x-1；③y=-1/x（x 下列函数：①y=-3x；②y=2x-1；③y=-1/x（x 2(x+y) 3x+3y=24 x+y/2x x y/2y= 1 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 Y=1/X X^2+Y^2=9 Y=|-2x| X=-3|sin y|