5(x-1)-2(y-2)=10 3x+4y = 2(y-1)
解方程组:(0.2x+0.1y)/2- (4x-y)/10=(x-y)/5+ (3x+0.5y)/30 (3x+2y-1
10/x+y+3/x-y=-5 15/x+y-2/x-y=-1(用换元法解此方程组)
已知:3x=8y.求(1)x+y/y (2)2x+3y/x-2y
若|x+2y-1|+y²+4y+4=0,求(2x-y)²-2(2x-y)(x+2y)+(x+2y)&
分式的加减:[(x/y-y/x)除以(x+y)+x(1/y-1/x)]除以1+x/y,其中x=5,y=2
化简求值:【(x+Y)(X-Y)-(X-Y)的平方+2Y(2-Y)】除4Y,其中X=1 Y=2
化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1
解方程组(1)2x-3y=10,-4x+y=5 (2)3x-2y=15,5x-4y=23
先化简再求值(x-y)(x-2y)-1/2(2x-3y)(x+2y),其中x=2,y=2/5
(5x-y)(y+5x)-(3y+2x)(3y-2x) x=1 y=2
化简求值(x+5y)(x+4y)-(x-y)(x+y),其中x=一又2/5,y=-1/7
已知x+y+2(-x-y+1)=3(1-y-x)-4(y+x-1),则x+y等于( )