3 ms·
Either you got the description wrong or I'm especially rusty - in that case, f''(x) = e^(-x), which is positive even when x is negative, so it doesn't always ha
by comex 13y ago
Either you got the description wrong or I'm especially rusty - in that case, f''(x) = e^(-x), which is positive even when x is negative, so it doesn't always have the same sign.
- wging 13y agoOh, crap, you're right. I read that as f''(x) must have the same sign as f(x).