Explanation:
Let x assume two values x₁ and x₂. Substituting these values in (1) and subtracting one from the other
f(x₂) - f(x₁) = 6x₂ + 1 - (6x₁ + 1) = 6x₂ - 6x₁= 6(x₂ - x₁) …………………..(A)
Equation (A) can be used to evaluate the difference between values of f(x) for any preassigned values of x.
In the present problem, x₁= 1 and x₂ = 2.
∴ (A) gives,
f(2) - f(1) = 6(2–1) = 6 . 1 = 6 (Answer).
