若|x-2|+|2y+6|=0,则x+y的值是（ ）若|x-2|+|2y+6|=0,则x+y的值是（ ）

若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 若x^2+y^2-6x+8y+25=0 则y/x-x/y的值是 若x^2+2x+y^2-6y+10=0,则x-y 若x^2+y^2-10x+6y+34=0,则x+y=? 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 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 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 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2x^2-6xy+9y^2-4x+4=0,则y/x-x/y=若2x^2-6xy+9y^2-4x+4=0,则y/x-x/y=? 若f(x+y,y/x)=x^2-y^2,则F(X,Y)= x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 (5)若x/2=y/3(y不为0）则x/y=____,x+y/y=___,y/x-y=___. 若x+y=1,x不等于0则x+(2xy+y^2)/x/(x+y)/x= 若2x-5y=0,则y：x 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 x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值 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=?