## jeffrey_beltran 3 years ago find derivative of g(x)=2tan^3 (4piex)

1. franciscanmonk

what have you got so far?

2. jeffrey_beltran

i replaced the 4piex to u

3. franciscanmonk

oh yeah. sorry i forgot this part of derivatives.

4. tjones89

try replacing tan(4 pi x) with u so you have 2(u)^3 then use the chain rule from there

5. jeffrey_beltran

ok i got: 1/2 x^2{(16-x^2)^-1/2(2x)}+(16-x^2)^-1/2 (x)

6. tjones89

can you show me the steps you took to get that?

7. jeffrey_beltran

i did the product rule and chain

8. tjones89

you dont have to use the product rule here

9. tjones89

the first step is to differentiate 2(u)^3 with respect to u

10. jeffrey_beltran

ok i get that

11. tjones89

what do you get?

12. jeffrey_beltran

1/2 x^2 (u)^1/2

13. tjones89

to differentiate 2(u)^3 with respect to u, you just need to use the power rule so it becomes 6u^2

14. jeffrey_beltran

oops i did the wrong prob!!

15. tjones89

oh so what is the problem you need to solve?

16. jeffrey_beltran

that same prob but i did the wrong work

17. tjones89

ok so can you differentiate 2u^3?