31,008 reputation
33396
bio website brilliant.org
location San Francisco, CA
age 30
visits member for 2 years, 1 month
seen Jan 27 at 12:56

Calvin Lin is the Math Challenge Master at Brilliant. He was born in Singapore, represented his home country at the International Mathematical Olympiad in 2001 and 2002, and trained the Singapore IMO team in 2005. Calvin studied economics and mathematics at the University of Chicago and graduated with a joint BA-MA in Mathematics in four years. While he was a student at the U of C, he continued training bright young mathematicians as an instructor for the Young Scholars Program for four years.


Jan
27
answered CHKMO 2015 and cubic equations
Jan
7
answered Given positive numbers $a, b, c, x, y, z$, such that $a + x = b + y = c + z = S$, prove that $ay + bz +cx < S^2$
Jan
5
comment Find the limit of $\lim_{n\rightarrow \infty}n^{2}((1+\frac{p}{n})^{q}-(1+\frac{q}{n})^{p})$
Hint: What happens when you expand everything with the binomial theorem? What constant term (no $n$) are you left with?
Jan
5
comment How prove such that $2^n-8$ is divisible by $n$, and $n$ has least three distinct prime factors.
You are really close. Continue in the same direction, where $p$ instead of being prime, is of the form $ p = qrs $ where $q, r$ are prime and $s$ is odd.
Jan
3
comment Are these graphs all bipartite?
@EricStucky Alright, fixed that. Thanks!
Jan
3
revised Are these graphs all bipartite?
added 72 characters in body
Jan
3
revised Are these graphs all bipartite?
added 72 characters in body
Jan
3
comment Are these graphs all bipartite?
@EricStucky Sorry, I thought that $ D$ must be an integer.
Jan
3
answered Center of gravity of a regular polygon
Jan
3
answered Are these graphs all bipartite?
Jan
3
comment Proving that the orthocenter lies on $OD$?
@Sawarnik It is an olympiad problem. I've seen it in the past. What I meant is that if the OP has no interest, then I can't be bothered.
Jan
3
comment Proving that the orthocenter lies on $OD$?
@Sawarnik The OP doesn't bother to respond to request for a diagram, so I can't really be bothered to do work for him either.
Jan
3
comment Proving that the orthocenter lies on $OD$?
Sorry, I meant that OIH does not look like a straight line. Can you add an image of your diagram?
Jan
3
answered Proving that the orthocenter lies on $OD$?
Jan
3
comment Proving that the orthocenter lies on $OD$?
I drew it in Geogebra and it does not look perpendicular at all.
Jan
1
revised A result of Erdős on increasing multiplicative functions
added 30 characters in body
Jan
1
comment A result of Erdős on increasing multiplicative functions
@quid For the record, I was in the midst of writing out the main steps. I wanted to check that spoiler works. It gets tricky with displaying equations in newline mode, which is why nothing else appeared.
Jan
1
revised A result of Erdős on increasing multiplicative functions
added 16 characters in body
Jan
1
revised A result of Erdős on increasing multiplicative functions
added 148 characters in body
Jan
1
revised A result of Erdős on increasing multiplicative functions
added 148 characters in body