2x-6y/x^2-9y^2 已知2x+6y+1=0

【2(x-y)(x-y)(x-y)-8(x-y)(x-y)(x+y)+6y(x-y)(x-y)]/2(x-y)(x-y) 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? 已知x^2-6xy+9y^2=0,求(x-y)/(x+y) 已知x-2y=3,则(2x+y-6)/(3x-y-9)=? 已知(x+y)(x+y-6)+9=0求2(x+y)的值 已知:(x+y)(x+y+6)+9=0 求2(x+y)的值 (x+y)^2+6(x+y)+9 已知方程组{2x+y=6 x+2y=9},求x+y与x-y的值 已知x+y=9,x-y=6,求x²-y²-2x-2y的值 已知6x+2y/9x-3y=6,那么(3x+y)平方/x平方-y平方 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 化简y(x+y)+(x+y)(x-y)-x^2 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 因式分解x(x+y)(x-y)-x(x+y)^2 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知x≠y,x^2-x=y^2-y,求x+y的值.