57
Chapter 6: Exponential and Logarithmic Functions and Tangent Lines
398. f x
x
x
x
( ) =
+
+
6
1
2
399. f x e e
x
x
( ) =
+
−
4
400. f x
x
x
( ) cos
=
+
8
2 1
401. f x x
x
( ) =
−
6
5
Finding Equations of
Tangent Lines
402–404 Find the equation of the tangent line at the
given value.
402. f
 
(x) = 3 cos x + πx at x = 0
403. f
 
(x) = x
2
– x + 2 at (1, 2)
404. f x e
x
x
( ) =
2
at x = 2
Finding Derivatives of
Functions Involving
Exponential Functions
390–401 Find the derivative of the given function.
390. f
 
(x) = e
5x
391. f x e
x x
( )
sin
=
+
4
392. f x
x
x
( ) =
+
(
)
3
1 2
393. f x
x
( ) log
=
+
5
3
5
2
394. f x e
x
x
x
( )
sin
cos
=
+
(
)
3
395. f x
x
x
( )
sin
= 5
396. f x
x
x
( ) =
+
(
)
−
4
4
3
397. f x
e
e
x
x
( ) ln
=
+
−

 

 
1
1