150/x+120/y=30 x-y=2

[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) y'-2y=(e^x)-x y'+2y/x=x通解 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 数学题已知p=x^/x-y-y^/x-y,q=(x+y)^-2Y(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 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 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 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20