x>0,y>0,2x+y=6 ,则x的平方乘y最大值怎么求,

x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值 若x^2+y^2-6x+8y+25=0 则y/x-x/y的值是 已知x^2-6y^2=-xy,x>0,y>0且x不等于y.则（x+3y）/（x-y）的值为_____? 若实数X,Y满足X²+Y²+4X-2Y +1=0,则X²-6X+Y²-2Y的最大值是多少 已知x.x+y.y+8x+6y+25=0,求代数式(x.x-4y.y)/(x.x+4xy+4y.y)-x/(x+2y)的值 （5x-6y)(x+y)=0(x不等于y),则y/x= 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知实数x满足x^2+2xy+y^2-(x+y)-6=0则x+y的值 若x-y不等于0,2x-3y=0,则分式(10x-11y)/(x-y)的值是（）?(10x-11y)/(x-y) =[(8x-8y)+(2x-3y)]/(x-y) =8为什么8X-8Y=8？(10x-11y)/(x-y)=[(8x-8y)+(2x-3y)]/(x-y)=8+(2x-3y)]/(x-y)=8+0=8 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 x^2+y^2-2x+4y-20=0则y/x的最大值,x+y的最大值 化简求值：已知x、y满足：x^2+y^2-4x+6y+13=0 求代数式 的值.(3x+y)^2-3(3x-y)(x+y)-(x-3y)(x+3y)急用！ 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? x^2+4y^2-6x+4y+10=0,求x^4-y^4/(x+2y)(x-2y)*x+2y/xy^2+y^3除以（x^2+y^2/y)^2的值 x^2+y^2+6x-4y+13=0求x,y,x^2-y^2的值 已知x-y-3绝对值+(2x+2y+10)的平方=0,则(x+y)(x-Y)=