## anonymous 5 years ago what is the derivative of rad(cos^3x)?

1. anonymous

2. anonymous

3. anonymous

$\sqrt{\cos ^{3}x}$

4. anonymous

the derivative of the inside is (.5)(3(-sinx)^2)^-1

5. anonymous

I mean the derivative of the whole thing

6. anonymous

on the outside is it -1/2?

7. anonymous

wait no type.. it is (.5) ((-sinx)(3(cosx)^2))^-1/2

8. anonymous

The constant term is -1/2 and the whole second part should be in the denomenator

9. anonymous

okay so when you chan the radical, you do the derivative of the cos. and in finding the derivative of cos, you have to chain it again?

10. anonymous

yes its a whole bunch of chains.

11. anonymous

haha, okay. are you taking ap test?

12. anonymous
13. anonymous

Ya i am.. taking BC calc

14. anonymous

did you take the AB last year?

15. anonymous

the test i mean

16. anonymous

No i just flexed it.

17. anonymous

I learned all of this in like middle school, and then now I'm just testing out of it so I can take college next year. calc 3 = fun

18. anonymous

haha. cool. i'll take the AB test next week. =] good luck with everything !

19. anonymous

yep you too.

20. anonymous

Ya I was wrong again.. use http://www.wolframalpha.com/input/?i=%28cos^3x%29^.5

21. anonymous

i didn't know you could use u sub for derivatives...

22. anonymous

They use it for the chain rule, but most of the time you don't see it.,