Timeline for Prove that $4x-x^4 \leq 3, x \in \Bbb R$ [closed]
Current License: CC BY-SA 3.0
12 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 28, 2018 at 0:24 | history | closed | JMP Claude Leibovici Ethan Bolker Xander Henderson♦ CommunityBot | Not suitable for this site | |
| Apr 27, 2018 at 4:29 | review | Close votes | |||
| Apr 27, 2018 at 13:51 | |||||
| Feb 21, 2018 at 8:30 | review | Close votes | |||
| Feb 21, 2018 at 9:54 | |||||
| Apr 14, 2013 at 22:59 | comment | added | Stefan Smith | you accepted an elegant answer that doesn't require calculus, but if you know a little calculus, it is easy: let $f(x) = 4x -x^4$. $f(x) \to -\infty$ as $|x| \to \infty$, so $f$ achieves a maximum value at some $x_0$. $f'(x_0) = 0$. $f'(x) = 4 - 4x^3$ so $x_0 = 1$. $f(1) = 3$ is the maximum value of $f$. | |
| Apr 14, 2013 at 9:45 | answer | added | gukoff | timeline score: 0 | |
| Apr 14, 2013 at 9:05 | answer | added | clark | timeline score: 15 | |
| Apr 14, 2013 at 9:04 | vote | accept | CommunityBot | ||
| Apr 14, 2013 at 8:53 | answer | added | bryan.blackbee | timeline score: 2 | |
| Apr 14, 2013 at 8:44 | answer | added | Phil Wang | timeline score: 7 | |
| Apr 14, 2013 at 8:43 | answer | added | AlexM | timeline score: 0 | |
| Apr 14, 2013 at 8:36 | answer | added | learner | timeline score: 12 | |
| Apr 14, 2013 at 8:34 | history | asked | user53386 | CC BY-SA 3.0 |