x+2y=5 2x+y=10

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai 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 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 / ( ) 已知2x-y=10,求[(x²+y²)-(x-y)²+2y(x-y)]/4y [x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 已知x,y满足约束条件{2x+5y>=10,2x-3y>=-6,2x+y { x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3