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)
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.
Prove that the exponential function ex is strictly increasing on R.
Let f (x) = ex ∴ Df = R
We are to prove that function f (x) = ex is strictly increasing. Here interval is not given. So we will prove that function ex is strictly increasing in its domain.
Now f ' (x) = ex
Three cases arise:
Case I.
Case II.
x = 0
∴ f ' (x) = ex = I > 0
Case III.