The line y = x + 1 is a tangent to the curve y 2 = 4x at the point
(1, 2)
(2, 3)
(1, -2)
(1, -2)
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.
Construct an example of a functions which is strictly increasing but whose derivative vanishes at a point in the domain of definition of the function.