Solution:

Given, two points P (5, 1) and G (1, -1)

Slope of the line (m) = y₂ – y₁/ x₂ – x₁

= -1 – 1/ 1 – 5

= -2/-4 = ½

So, the equation of the line is

y – y₁ = m (x – x₁)

y – 1 = ½ (x – 5)

2y – 2 = x – 5

x – 2y – 3 = 0

Now, if point R (11, 4) is collinear to points P and Q then, R (11, 4) should satisfy the line equation

On substituting, we have

11 – 2(4) – 3 = 11 – 8 – 3 = 0

As point R satisfies the line equation,

Hence, P, Q and R are collinear.