x+2y=6 2x+y=9则x+y值是多少?

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 诺{x+2y=6,2x+y=9则x+y=__ 已知x-2y=3,则(2x+y-6)/(3x-y-9)=? x+2y=6 2x+y=9则x+y值是多少? x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 设f(x+y,x-y)=x^2-y^2,则f(x,y)= 若f(x+y,y/x)=x^2-y^2,则F(X,Y)= 已知f(x+y,y/x)=x^2-y^2,则f(x,y)= （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 [(2x-y)(2x+y)+y(y-6x)]÷2x=? 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1