已知x²+y²+4x-8y+20=0 x=?y=?(x²+y²)²+y
已知x²+y²-8x+6y+25=0,求(x-y+4xy/x-y)(x+y-4xy/x+y)
已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y²
已知x²+4y²-6x+8y+13=0,求x-y/x+y的值.
已知x,y满足x²+y²-4x+6y+13=0则(3x+y)²-(3x+y)(3x-y)的
已知非零有理数x,y满足x²-4xy+4y²=0,求x-y/x+y-y-x/x+y的值.
已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y
若|x+2y-1|+y²+4y+4=0,求(2x-y)²-2(2x-y)(x+2y)+(x+2y)&
已知y+y'*x²=0,求y=?
已知X²+3XY-4Y²=0(Y≠0)求X-Y/X+Y
已知x+y=4,x²-y²=20,则x-y=?
已知x-y=4,x²-y²=20,求x-y的值
已知x²+4x+y²-2y+5=0,则x+y=