已知(x-y+1)^2+| xy-2x-2y-7 |=0,求①x^2+y^2 ②4x^2 y^2-x^4-y^4
已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值?
已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y²
已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)}
已知x,y>0 2x+y+3=xy 求5x+4y最小值
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*
已知4x=9y求(1)x+y/y (2)y-x/2x
已知x^2+y^2=10,x+y=4,求①2xy ②(x-y)^2 ③x-y ④x^2-y^2
已知x.x+y.y+8x+6y+25=0,求代数式(x.x-4y.y)/(x.x+4xy+4y.y)-x/(x+2y)的
已知x²+y²-2x+4y+5=0,求X^4-y^4/2x^2+xy-y²·2x-y/xy
已知x^2+y^2+x^2y^2-4xy+1=0 求(x-y)^2008-(xy)^2008
已知X²+Y²+X²Y²-4XY+1=0 求:(X-Y)^2008-(XY)^2
已知(x+2)^2+|x+y+5|=0,求3x^2y-[2x^2y-(2xy-x^2y)-4x^2]-xy