若2x-y=5,则15-4x+2y

若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 若5x+3y=3x+4y=x+2y+6,则x+y=___ 若x/y=4/3 则3x+2y/2x-5y= 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若x-2y=5,则式子12-x+2y=.以知3x-4y=2x+y则x∶y= 若|2x-y+5|+(x+2y-4)的平方=0,则（2x-y)的三次方-（x-3y)(y-2x)的平方 若x,y,z成等差数列,则(z-x)^2-4(x-y)(y-x)= 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 若x+y=4,则多项式1/2(x+y)+4(x-y)-3（x-y）-3/2(x+y)-x+y值是（） 若x^2-4y^2=-15,2y-x=5,则x+2y=____ 若f(x+y,y/x)=x^2-y^2,则F(X,Y)= 2（x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 x*x+2x+y*y-4y+5=0 x= y= 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27