a) < -- function is differentiable everywhere except 1/2*pi and -1/2*pi...correct??

b) ...dont know where this one is differentiable

c) <---- also dont know how to find where this one is differentiable..

please help

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- Feb 11th 2008, 12:00 AMb00yeah05where are these functions differentiable??
a) < -- function is differentiable everywhere except 1/2*pi and -1/2*pi...correct??

b) ...dont know where this one is differentiable

c) <---- also dont know how to find where this one is differentiable..

please help - Feb 11th 2008, 12:09 AMJhevon
just look where the functions are undefined or have cusps. for (a), it is not differentiable anywhere sin(x) = 0. and that is at infinitely many points (not including 1/2 pi and -1/2 pi), but rather, at k*pi, for k an integer

for (b), the logarithm is undefined at zero, and hence, is not differentiable there

try (c)

if you want to be sure of these answers, try using the limit definition of a derivative, the limit will not exist where the function is not differentiable - Feb 11th 2008, 12:11 AMearboth
- Feb 11th 2008, 12:22 AMb00yeah05
c is the hardest one...the first derivative for c i got --- >

i cant simplify it anymore...so you solve the denominator for 0?? - Feb 11th 2008, 12:28 AMmr fantastic
- Feb 11th 2008, 12:29 AMb00yeah05
ahhhhh yes...this one was quite tricky..but thanks for the help mr.fantastic...

- Feb 11th 2008, 12:45 AMmr fantastic