2/x+y-1/x-y=3 3/x+y-4/x-y=10
{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
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=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai
{3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1
(3x-y)^2+(3x+y)(3x-y),x=1,y=-2
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
{4/(x+y)+6/(x-y)=3 {9/(x-y)-1/(x+y)=1
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27