若(x-y)^2+|5x-7y-2|=0,则xy的平方根为

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 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 x*x+2x+y*y-4y+5=0 x= y= {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 (5)若x/2=y/3(y不为0）则x/y=____,x+y/y=___,y/x-y=___. 若2x-5y=0,则y：x 若x>0,y>0,且√x(√x+√y)=3√y(√x+5√y),求2x+2√x*√y+3y/x-√x*√y+y {2x+y/3-2y=0 2(2x+y)-5=7y 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 若|x+y-3|+(x-y-5)^2=0,则x)^2-y^2= 已知(x-y)^2+|5x-7y-2|=0,求x,y的值. 若5x+y/7x+10y=1/2,则x/y=? 若7x+10y分之5x+y=1/2,则x/y= 若（5x+y）／(7x+10y)=1/2则x/y=