4y+2x=72

{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 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 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 已知4x=9y求(1)x+y/y (2)y-x/2x (x+y)(x+2y)(x+3y)(x+4y)=-40 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 2x-y=2,求[(x²+y²)-(x-y)²+2y(x-y)]÷4y 已知2x-y=10,求[(x²+y²)-(x-y)²+2y(x-y)]/4y [(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x= 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y²