question_answer 1)

Show that points A (a, b + c), B (b, c + a), C (c, a + b) are collinear. 

Answer:

The point A (a, b + c), B (b, c + a) and C(c, a + b) are collinear, if area of a triangle having these vertices is zero.       Here             [By Operating ]                                     C(c, a + b) are collinear.