Question

What's the second derivative of f(x)= sec^2 (pix)?

Answer 1

cos^2

Answer 2

^incorrect.

Answer 3

i thnk so

Answer 4

The answer would be:
\[\frac{d}{dx} \left( \frac{d}{dx}(\sec^2(\pi x)\right)=\frac{d}{dx} \left( 2 \pi(\sec^2( \pi x)\tan(\pi x) \right)\]
From the product rule. If you look CAREFULLY you see that if we differentiate whats left we do the product rule, one of them involves the derivative of sec^2(pi x) which we JUST FOUND, so use that result to get:
\[4 \pi^2 \sec^2(\pi x)\tan^2(\pi x)+2 \pi^2 \sec^4(\pi x)\]

Answer 5

Not cos^2

Answer 6

check derivative section
http://www.wolframalpha.com/input/?i=2+%CF%80+sec%5E2%28%CF%80+x%29+tan%28%CF%80+x%29&lk=1&a=ClashPrefs_*Math-