Big big help do not understand

[dagreat45]

Determine the sub-intervals of [−10,12] on which the function f(x) defined below has the following properties. Enter a comma-separated list of sub-intervals, or enter none if no such sub-intervals exist.

f(x)=x^7(x+4)^8​

a) On which sub-intervals is the function increasing?

f(x) is increasing on:
​

b) On which sub-intervals is the function positive?

f(x) is positive on:
​

c) Finally, where does the function achieve its absolute minimum? Enter a single value of x.

f(x) has an absolute minimum when x=​

 

[daon2]

Read the rules.

http://www.freemathhelp.com/forum/threads/78006-Read-Before-Posting

 

[HallsofIvy]

Determine the sub-intervals of [−10,12] on which the function f(x) defined below has the following properties. Enter a comma-separated list of sub-intervals, or enter none if no such sub-intervals exist.

f(x)=x^7(x+4)^8

a) On which sub-intervals is the function increasing?​

f(x) is increasing on:​

What is the derivative of this function? What does that tell you about "increasing" or "decreasing"?
​

b) On which sub-intervals is the function positive?

f(x) is positive on:​

This should be easy. The product of an odd number of "negatives" is negative, the product of an even number is positive. What can you say about \(\displaystyle (x+4)^8\)?
​

c) Finally, where does the function achieve its absolute minimum? Enter a single value of x.

f(x) has an absolute minimum when x=​