x+y=20 5x-2y=58
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
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
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
解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7
6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
x-y / 5y= (y-x)^2 / ( )
4X+2Y=58 X+Y=20 X=?Y=?
已知x*x+4x+y*y-2y+5=0,则x*x+y*y=?
[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013