1/2x-1/3y=1 -1/3x-y=2/3 0.4x+0.3y=0.7 11x-10y=1 2/5x-1/3y+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
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1
已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
2(x+y) 3x+3y=24 x+y/2x x y/2y= 1
(2x+y-1)(2x-y+1)-(3x+y)(3x-y),其中x=5分之1,
{ x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3
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
[(2x+y)^2+(y+2x)(y-2x)-2y(4x-y)]/4y,其中x=1/2,y=1/3
先化简,再求值:[(x+y)(x-y)-(x-y)^2+2y(x-3y)]/(-4y),其中x=1,y=-2