{4/(x+y)+6/(x-y)=3 {9/(x-y)-1/(x+y)=1
{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
解方程组{4/x+y+6/x-y=3, 9/x-y-1/x+y=1
解方程组:{4/x+y+6/x-y=3 9/x-y-1/x+y=1}
{3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1
已知4x=9y求(1)x+y/y (2)y-x/2x
9y=3x-(x-1),4(x+y)-(2x+4)=8y
化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1
化简求值:(7x-2y)(3x-2y-1)-(4x+3y)(9x+6y),其中x=2,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=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
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