Question

Prove that point $(1,1),(-2,7)$ and $(3,-3)$ are collinear.

Answer 1

A (1, 1)

B (-2, 7)

C (3, -3)

Slope of AB $=\frac{7-1}{-2-1}=\frac{6}{-3}=-2$

Slope of BC $=\frac{7-\left(-3\right)}{-2-3}=\frac{10}{-5}=-2$

Slope of AC $=\frac{1-\left(-3\right)}{1-3}=\frac{4}{-2}=-2$

Since slope of AB = Slope of BC = Slope of AC

Hence, points A,B,C are collinear.