{2x+3y=1,4x-y=5 {x-2y=1,3x=2y {4x-3y=15,3x+2y=7 {3y-4x=6,3x-
{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)+...-(
x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20
{(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20
4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
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
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
(x+y)(x+2y)(x+3y)(x+4y)=-40
若2x-3y+4=0则x(x*x-1)+x(5-x*x)-6y+7
9y=3x-(x-1),4(x+y)-(2x+4)=8y