## sandy524 Group Title find the derivative of f(x) = 3x cos 6x . one year ago one year ago

1. Mimi_x3 Group Title

$\frac{d}{dx}3xcos6x$ Do you know the product rule?

2. sandy524 Group Title

yes

3. Mimi_x3 Group Title

So, what have you done?

4. sandy524 Group Title

but how would i use it in this case

5. Mimi_x3 Group Title

Where are you having problems?

6. sandy524 Group Title

may someone please show me step by step how to do this. my professor sucks and is currently being investigated by the math dept here because of it so yeah...

7. tinagca Group Title

8. tinagca Group Title

That site will provide you with a step by step! :D

9. sandy524 Group Title

mathway is not credible

10. Mimi_x3 Group Title

Well, have you atleast tried it?

11. tinagca Group Title

How i learn a lot from that site...

12. tinagca Group Title

You just have to sign up to get the step by step part!! :) It helps me a ton...

13. sandy524 Group Title

i have missed many questions from its wrong answers. wolframalpha is more reliable

14. tinagca Group Title

Okay. maybe you just type them in wrong... it always helps me :D

15. tinagca Group Title

I dont use it for tests though... i use it for help... you use it for tests?

16. sandy524 Group Title

okay sure but anyways thanks bye. now back to the question i need help with

17. Mimi_x3 Group Title

@tinagca: Please don't divert people to another site; when someone is trying to help them.

18. tinagca Group Title

Mkay! later :D

19. tinagca Group Title

I was trying to give her a step by step site :o

20. Mimi_x3 Group Title

That was retarded; interjecting out of the blue.

21. sandy524 Group Title

please folks i really need help the bantering can be spared

22. tinagca Group Title

Oh shut up. like seriously i was trying to help then you guys started being rude. So whatever, a simple thank you and just saying " Oh i already tried that site" would have been fine.

23. zepdrix Group Title

|dw:1350314820570:dw|

24. sandy524 Group Title

thank you zepdrix u are always so helpful

25. zepdrix Group Title

so do it piece by piece :) We have a (3x)', what is the derivative of 3x? :D

26. sandy524 Group Title

simply 3

27. zepdrix Group Title

ok cool, so the first term will simplify to (3)(cos6x). Hmm now we have a (cos6x)' on the right side. We'll take the derivative of the outermost function (cosine) Then "chain" (multiply by the derivative of the inside (6x)' ) So whats the derivative of cos6x? :D

28. sandy524 Group Title

-6sin(6x)

29. sandy524 Group Title

right

30. zepdrix Group Title

Yay sandy \c:/

31. tinagca Group Title

You should give @zepdrix a medal @sandy524 ...i mean, that was a great answer!

32. zepdrix Group Title

lol tina c:

33. tinagca Group Title

:) I gave you a medal! :D

34. sandy524 Group Title

ok so after that what do we do

35. zepdrix Group Title

Just combine the pieces together and simplify :D So far we've figured out that the derivative is (3)(cos6x) + (3x)(-6sin6x) =3cos6x -18xsin6x Make sense? :D