Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Suppose the derivative of a function $f$ is below. On what interval is $f$ increasing?

$$ f'(x) = (x+1)^4(x-5)^3(x-7)^6 $$

share|improve this question
2  
Where does the second derivative come in? –  Arturo Magidin Nov 28 '11 at 2:10
1  
Why use the Second Derivative Test (en.wikipedia.org/wiki/Second_derivative_test)? The hint/answer provided below should answer your questions. –  JavaMan Nov 28 '11 at 2:14

1 Answer 1

$f(x)$ is increasing wherever $f'(x) > 0$. Thus, it follows that $f(x)$ is increasing wherever:

$$(x+1)^4 (x-5)^3 (x-7)^6 > 0$$

I hope you can take it from here.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.