x,y为正数,x+y=1,证明x²+y²+1/x²+1/y²≥17/2
已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y
1、y-x/x²-y²
[(y-2x)(-2x-y)-4(x-2y)²]*2y,其中x=1,y=2
若正数x,y满足x²-y²=2xy,求(x-y)/(x+y)的值
正数x,y满足x²-y²=2xy,求x-y/x+y的值
若|x+2y-1|+y²+4y+4=0,求(2x-y)²-2(2x-y)(x+2y)+(x+2y)&
[2x²-(x+y) (x-y)] [(-x-y) (y-x)+2y²] 其中x=1,y=2
化简求值 【2x²-(x+y)(x-y)][(x+y-1)(x-y+1)+1-2y],其中x=-1,y=-2
若|x+y-1|+(x-y-2)²=0,求代数式(x+2y)(x-2y)-(2x-y)(-y-2x)的值.
简化|x-y+1|-2|y-x-3|+|y-x|+5其中y为负数,x为正数
已知x²+y²+5=2x+4y,求代数式(2x²-(x+y)(x-y))x((x+y-1)
已知x+y=1,xy=-二分之一,求x(x+y)(x-y)-x(x+y)²