若4x²－81y²=10,2x－9y=2,则2x＋9y=

已知4x=9y求(1)x+y/y (2)y-x/2x 若|x+2y-1|+y²+4y+4=0,求（2x-y）²-2（2x-y)(x+2y)+(x+2y)& 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 若实数X,Y满足X²+Y²+4X-2Y +1=0,则X²-6X+Y²-2Y的最大 已知2x-y=10,求式子[(x^2+y^2)-(x-y)^2+2y(x-y)]/4y (4xy-2y²)/4 已知4x²+y²-4x-6y+10=0求（2/3x（√9x）+(y²√x/y³) 已知4x²+y²-4x-6y+10=0,求[(2/3)x√(9x)+y²√(x/y 已知4x²+y²-4x-6y+10=0,求(2/3√9x+y²√x/y³)-(x 已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y 若【2x²-3y²-10y+5】²+根号x-2y,则x= y= [(y-2x)(-2x-y)-4(x-2y)²]*2y,其中x=1,y=2