Question
Show that the function f (x) = 2 x + 3 is a strictly increasing function on R.
Solution
Let x1 , x2 ∊ R and let x1 < x2
Now x1, < x2
⇒ 2x1 < 2x2
⇒ 2x1 + 3 < 2x2 + 3
⇒ f (x1) < f (x2)
⇒ f is an increasing function on R.
