9(x+y)²-4(x-y)²=?
函数f(x,y)=x²+y²-2x+4y+9的最小值
已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y²
已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y
(x-y)³+9(x-y)-6(x-y)²
(2x-y)²-4(x-y)(x+2y)
化简:(2x-y)²-4(x-y)(x+y)
已知集合M={(x,y)|x,y为实数,且x²/4-y²/9=1},N {(x,y)|x,y为实数,
[(y-2x)(-2x-y)-4(x-2y)²]*2y,其中x=1,y=2
(x+y)²+4(x+y)-5
若|x+2y-1|+y²+4y+4=0,求(2x-y)²-2(2x-y)(x+2y)+(x+2y)&
x²+xy/(x-4y)(x+y),其中x=4,y=-1
已知x,y满足x²+y²-4x+6y+13=0则(3x+y)²-(3x+y)(3x-y)的