Derivatives of
Exponential Functions
Natural Exponential Function
If f ( x ) = ln x , then

Properties:

f −1 ( x) = e x
Solving Exponential – Natural Log Functions:
Rewrite one as the other with base e

Example: Solve

ln( x + 1) = 6
2

2 ln ( x +1) = 6
ln ( x +1) = 3

e = x+1
3

x= e −1
3
d  x x
b  = b ln b
dx
d  u u
du
4.
b  = b ln b ×
dx
dx
3.

Example: Find the derivative

f ( x) = e
f '( x) = e

−

−

1
x2

1
x2

2
× 3
x
Differentiate the
following
functions:

1.
2.
3.
4.

d  x x
2  = 2 ln 2
dx
d  −2 x  −2 x
e  = e ×(−2) = −2e−2 x

dx
d  x3  x3
2
2 x3
e  = e ×3x = 3x e
dx
d  cos x  cos x
e  = e ×(−sin x) = − ( sin x ) ecos x

dx
Use logarithmic
differentiation to find
sin x 
d 2
( x +1) 

dx 

Solution:

y = ( x +1)
2

sin x

ln y = ln ( x +1)
2

sin x

ln y = ( sin x ) ln ( x 2 +1)

1 dy
1
= ( cos x ) ln ( x 2 +1) + ( sin x ) 2 2x
y dx
x +1
2x ( sin x ) 
dy 
2
= ( cos x ) ln ( x +1) +
 ×y
2
dx 
x +1 

sin x
2x ( sin x )  2
dy 
2
= ( cos x ) ln ( x +1) +
 ×( x +1)
2
dx 
x +1 
Let’s Practice!!!
Differentiate each of the following:

1.

ex
y=
ln x

2.

y = ( x + 3)

3.

y = ln ( cos−1 x )

4.

y = cot −1 x

2

ln x

4.3 derivative of exponential functions

  • 1.
  • 2.
    Natural Exponential Function Iff ( x ) = ln x , then Properties: f −1 ( x) = e x
  • 3.
    Solving Exponential –Natural Log Functions: Rewrite one as the other with base e Example: Solve ln( x + 1) = 6 2 2 ln ( x +1) = 6 ln ( x +1) = 3 e = x+1 3 x= e −1 3
  • 4.
    d  xx b  = b ln b dx d  u u du 4. b  = b ln b × dx dx 3. Example: Find the derivative f ( x) = e f '( x) = e − − 1 x2 1 x2 2 × 3 x
  • 5.
    Differentiate the following functions: 1. 2. 3. 4. d x x 2  = 2 ln 2 dx d  −2 x  −2 x e  = e ×(−2) = −2e−2 x  dx d  x3  x3 2 2 x3 e  = e ×3x = 3x e dx d  cos x  cos x e  = e ×(−sin x) = − ( sin x ) ecos x  dx
  • 6.
    Use logarithmic differentiation tofind sin x  d 2 ( x +1)   dx  Solution: y = ( x +1) 2 sin x ln y = ln ( x +1) 2 sin x ln y = ( sin x ) ln ( x 2 +1) 1 dy 1 = ( cos x ) ln ( x 2 +1) + ( sin x ) 2 2x y dx x +1 2x ( sin x )  dy  2 = ( cos x ) ln ( x +1) +  ×y 2 dx  x +1  sin x 2x ( sin x )  2 dy  2 = ( cos x ) ln ( x +1) +  ×( x +1) 2 dx  x +1 
  • 7.
    Let’s Practice!!! Differentiate eachof the following: 1. ex y= ln x 2. y = ( x + 3) 3. y = ln ( cos−1 x ) 4. y = cot −1 x 2 ln x