+0  
 
+1
869
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avatar+605 

1. For which intervals is the function positive?

 

(−6, −2)

(−2, 4)

(4, 8]

[−8, −6)

 

 

2. Which answer describes the function f(x)=x5+2x ?

 

neither

even

odd

 Feb 12, 2018
 #1
avatar+8945 
+1

1.   Since  y  =  f(x)  ,  f(x)  is positive at every point that has a positive  y  value.

 

f(x) is positive when  x  is in the intervals  [-8, -6)  and  (-2, 4) .

 

2.   f(x)  =  x5 + 2x

 

To find out if this function is even or odd, we need to find  f(-x) .

 

f(-x)   =   (-x)5 + 2(-x)

 

f(-x)   =   - x5  -  2x

 

f(-x)   =   (-1)(x5 + 2x)

 

f(-x)   =   (-1)( f(x) )

 

Since  f(-x)  =  -f(x) ,  f(x) is an odd function.

 Feb 12, 2018

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