( X^2 + 4Xx +4 ) + ( Y^2 - 6Y + 9) = 0 ( X + 2 )^2 + ( Y - 3 )^2 = 0 所以,两个平方之和等于0,则两个都为0 X = -2.Y = 3 2X + 3Y = -4 + 9 = 5