Question
Without using the derivative show that the function f (a) = 7x – 3 is a strictly increasing function on R.
Solution
Let x1, x2 ∊ R and let x1< x2
Now x1 < x2 ⇒ 7 x1, < 7 x2 ⇒ 7 x1 – 3 < 7 x2, – 3
⇒ f (x1) < f (x2)
∴ f is strictly increasing function in R.
