x+y=20 3x=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 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) 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 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=20-6 3x+y=30 x+y=20 3x=y 1/(x+y)-1/(x+y)=3/20 2/(x+y)+3/(x-y)=19/20 这是 3(x+y)+2(x-y)=20 0.3x+0.6y=60 x=?y=? 已知：x-y=1,x+y=-7,求代数式3（x+y)+20(x-y)-5的值