Mathematics
ETS1331's user avatar
ETS1331's user avatar
ETS1331's user avatar
ETS1331
  • Member for 6 years, 7 months
  • Last seen more than a week ago
  • Washington, United States
Profile Activity
Stats
1,292
reputation
16k
reached
33
answers
1
question
Communities
View all
Badges
View all badges
This user doesn’t have any gold badges yet.
11
silver badges
23
bronze badges
Top tags
View all tags
30
Score
8
Posts
24
Posts %
22
Score
6
Posts
18
Posts %
20
Score
4
Posts
12
Posts %
15
Score
3
Posts
9
Posts %
14
Score
4
Posts
12
Posts %
10
Score
7
Posts
21
Posts %
Top posts
View all questions and answers
All Questions Answers
Score Newest
answer
11
Olympiad Algebra Practice Question
Aug 31, 2019
answer
11
Show that $\forall (a, b, c) \ \in \mathbf{R}: \frac{a^2}{b^2} + \frac{b^2}{c^2} + \frac{c^2}{a^2} \ge \frac{b}{a} + \frac{c}{b} + \frac{a}{c}$
Mar 12
answer
6
Evaluate $\sum\limits_{k=1}^n (k^{3} +k^{2} +1) / (k^{2} +k)$
Feb 10, 2019
question
5
Does removing all numbers in the harmonic series with a units digit of 9 affect the series?
Feb 28, 2017
answer
5
How do you compute the sum of k * a^k
Feb 10, 2019
answer
5
A Straightforward optimization problem, but without calculus
Jan 16, 2021
answer
4
Combinatorial proof of $\sum_{k=0}^{n} \binom{3n-k}{2n} = \binom{3n+1}{n}$
Jul 17, 2019
answer
4
How many ways to place plus and minus signs in front of numbers from 0 to 12 so that the sum is divisible by 5?
Nov 26, 2022
answer
4
Prove that the number of "good" subsets in $A$ and the number of "good" subsets in $B$ have the same parity.
Nov 26, 2022
answer
4
For all natural numbers $a_i$ of the set $\{1,2,\dots\,2017\}$ show that $\sum_{i=1}^{2017}\frac{{a_i}^2-i^2}{i} \geq 0$
Nov 28, 2022

Your privacy

By clicking “Accept all cookies”, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy.