## anonymous one year ago How would I solve this?

1. anonymous

2. campbell_st

start by rewriting the function in index form $f(x) = \frac{-9}{x}~~~~or~~~~~f(x) = -9x^{-1}$ now you can find the derivative when you get the derivative just substitute x =12 and calculate an answer

3. campbell_st

or if you wait someone always gives the answer

4. anonymous

Thanks.

5. anonymous

Well how do I find the derivative, I'm not familiar with the process.

6. anonymous

@campbell_st

7. campbell_st

ok... well if you don't understand the process of differentiation, then it's extremely difficult to complete this question. so have you studied any calculus..?

8. anonymous

I do not understand differentiation that well, as I am self taught.

9. campbell_st

ok, well here are some good online notes that take you through the process and methods but the basic thing for your question, now it's rewritten is to use this if $f(x) = ax^n$ then the derivative is $f'(x) = n \times ax^{n -1}$ here are the notes http://tutorial.math.lamar.edu/Classes/CalcI/DerivativeIntro.aspx hope they help

10. anonymous

11. anonymous

@campbell_st

12. anonymous

I think it is 1/16 is that correct?

13. campbell_st

that's correct

14. anonymous

Thanks :)