1.方程x^2y^2+9x^2+y^2-12xy=9的负整数解是?

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 解方程（y-x-5)y'-y+2=0 解方程{2x+y=2、-x+y-5 解方程：,(100-x-y)-(x+y)=2 方程 x-2y=45 x+y=65 化简y(x+y)+(x+y)(x-y)-x^2 3x+y=9-y 5x-2=6-y 解方程 (x+y)(x-y)-(x-y)^2如题 (x+y)(x-y)-(x-y)^2 【2(x-y)(x-y)(x-y)-8(x-y)(x-y)(x+y)+6y(x-y)(x-y)]/2(x-y)(x-y) 因式分解x(x+y)(x-y)-x(x+y)^2 用带入消元法解方程：｛x+y=9,3(x+y)+2x=33 方程2y=x中,如果y=9,那么,x=( ),x+4=( ) 9(x-y)-12(y-x)^2 (x+y)^2+6(x+y)+9 (x+y)^2-9(x+y)+18 微积分方程求解e^x + (e^x cot y + 2y csc y)y' = 0 解方程：(x-2y)^2n/(2y-x)^2n-1+(2x-y)(-2x-y)+(x-y)(-x+y) x+x+x-y-y=12 y+y+y-x-x=2 求x=?y=?不能用方程用奥数解法