45
Chapter 4: Derivative Basics
285. f x
x
( ) = 1
1
−
286. f
 
(x) = x
3
+ 3x
287. f x x
( ) =
+
1
5
2
288. f x
x
x
( ) =
+
+
2 1
4
289. f x x
x
( ) =
+
+
2
1
3
290. f x
x
( ) =
+
2 1
3
Finding the Derivative by
Using the Definition
277–290 Find the derivative by using the definition
f x
f x h f x
h
h
′
( ) =
+
lim
(
) ( )
→
−
0
.
277. f
 
(x) = 2x – 1
278. f
 
(x) = x
2
279. f
 
(x) = 2 + x
280. f x x
( ) = 1
281. f
 
(x) = x
3
– x
2
282. f
 
(x) = 3x
2
+ 4x
283. f x
x
( ) =
284. f x
x
( ) = 2 5
−