Question

Determine if the points $(1,5),(2,3)$ and $(-2,-11)$ are collinear.

Answer 1

If three points are to be collinear then the slope of the lines formed by joining any two of them should be equal.

Let's check it out:

Let the points be: A(1,5),B(2,3),C(−2,−11)A(1,5),B(2,3),C(−2,−11)

here $y2=3,y1=5$ & $x2=2,x1=1$

Thus, slope of $AB=\frac{(3-5)}{(2-1)}$

= -2

Now let's the slope of AC;

Slope $AC=\frac{(-11-5)}{(-2-1)}$

=$\frac{16}{3}$

Thus we see that the slope of AB &AC are not same therefore the points A,B &C are non-collinear.