# Nth derivatives

1. Aug 28, 2013

### makar

1. The problem statement, all variables and given/known data

how to find nth derivatives cos^12x and a-x/a+x

2. Relevant equations

3. The attempt at a solution

2. Aug 28, 2013

### makar

help please..

3. Aug 28, 2013

### LeonhardEu

Don't panic. Since you know derivation is quite easy to deduce them. Write the first two or three derivatives and see the pattern. I 'll give an example to understand:
(sinx)' = cosx = sin(x+pi/2)
(sinx)'' = (cosx)' = -sinx= sin(x+pi), (sinx)''' = -cosx = sin(x+3pi/2), (sinx)(4) = sinx = sin(x+2pi).
SO the n-nth derivative of sinx is sin(x + n*pi/2)
Yours are all the same way.

4. Aug 28, 2013

### tiny-tim

hi makar! welcome to pf!

try it, and show us what you get

start with the first few derivatives of cos12x

(you may spot a pattern)

5. Aug 28, 2013

### lurflurf

6. Aug 30, 2013

### makar

thank u everyone for helping me..

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