若x²-4x+y²+2y+5=0,求x和y的值.

若|x+y-1|+（x-y-2)²=0,求代数式（x+2y)(x-2y）-（2x-y)(-y-2x)的值. 已知x² +y²+5/4=2x+y,求y-x的值 1.若x²+y²-4x+2y+5=0,求x,y的值. 若x²-4x+y²+2y+5=0,求x、y的值. 若X-2Y+6+（X+Y+12）²=0,求4X+ 5Y的值 实数x y满足x≥y≥1和2x²-xy-5x+y+4=0求x+y之值 如果(2x-3y+5)²+|x+y-2|=0,求x和y的值. 若|x+2y-1|+y²+4y+4=0,求（2x-y）²-2（2x-y)(x+2y)+(x+2y)& 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X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? (1)已知x+y=6,x²-y²=5,求x-y的值（2）若x+y=3,x²+y²