Using determinant

Given: – (1, 2) and (3, 6) are collinear points

Tip: – For Three points to be collinear, the area of the triangle formed by these points will be zero

Now, we know that,

Vertices of a triangle are (x₁,y₁), (x₂,y₂) and (x₃,y₃), then the area of the triangle is given by:

Now,

Let, 3^rd point be (x,y)

Substituting given value in above formula

⇒

Expanding along R₁

⇒

⇒ [x(– 4) – y(– 2) + 1(0)] = 0

⇒ – 4x + 2y = 0

⇒ y = 2x

It’s the equation of line