如果x/3y=y/(2x-5y)=(6x-15y)/xx/3y=y/(2x-5y)=(6x-15y)/x 求(4x^2-5xy+6y^2)/(x^2-2xy+3y^2)=?

x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 如果方程组x-y=a-3,2x+y=5的解x、y满足x>0,y 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 如果A={（x,y）|x,y+2>0},B={（x,y）|2x+3y-6>0},C={（x,y）|x-4 x.y是非零实数,如果2x-y/3y=y/x,那么x/y= 如果x/y=3则x+y/y （x+y-5)*（x+y-5)+（x-y+3)=0 x*x-y*y 已知:3x-5y=0,求x/y,x-y/y,x-y/x 3x+5y-(x+y)=6 2(x+y)-3x=-7 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 （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