29,734 reputation
32794
bio website brilliant.org
location San Francisco, CA
age 29
visits member for 1 year, 6 months
seen 4 hours ago

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.


1d
comment I am searching for an unusual real-valued function.
-1 I don't think you can "assume $f(xy) = f(x) f(y)$", but otherwise this is nice.
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comment Websites for math tests/quizzes
You can check out Brilliant.org's practice section. We are building out the Geometry and Calculus sections, which should be out by the end of the month.
1d
comment Find odd numbers $(o_1,o_2,o_3,o_4)$ such that $o_1^2-o_2^2=2(o_3^2-o_4^2)$ such that $o_1>o_2$ and $o_3>o_4$
There are solutions, like with $ p+q = r+s = 10$ and $ p-q = 4, r-2 = 2$, which gives us $p = 7, q = 3, r = 6, s = 4$.
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revised N points and N perpendiculars
added 48 characters in body
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answered N points and N perpendiculars
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comment N points and N perpendiculars
@Semiclassical Potential gap is that "parallel" doesn't invert to "concentric". Also, you only go from a line to a circle if the center of inversion is on the line.
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comment N points and N perpendiculars
How is it possible that "no two such perpendiculars intersect". Are these line segments, or lines? Otherwise, the perpendicular lines are not parallel, so much intersect.
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revised Help with complicated functional equation
added 870 characters in body
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answered Help with complicated functional equation
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answered Finding the value of this product
1d
comment Is this graph connected
Are you allowed to use negative integers, or is this graph only on positive integers?
1d
answered Jordan chain when matrix has only one eigenvalue.
1d
comment Nonlinear system of equations / factoring two-variable cubic over $\mathbb{R}$
@dmk Edited.......
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revised Nonlinear system of equations / factoring two-variable cubic over $\mathbb{R}$
added 148 characters in body
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answered Nonlinear system of equations / factoring two-variable cubic over $\mathbb{R}$
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comment Nonlinear system of equations / factoring two-variable cubic over $\mathbb{R}$
Why can't we have $ u=v=w$ equal to some other constant? Since you said you used barycentric coordinates, do you want those to sum up to 1?
Jul
18
comment Help with complicated functional equation
This is an IMO 2001 shortlist problem.
Jul
17
comment Regular Pentagon is the Unique Largest Two-Distance Set in the Plane
@Denis Thanks. I've edited the proof to approach it differently.
Jul
17
revised Regular Pentagon is the Unique Largest Two-Distance Set in the Plane
added 476 characters in body
Jul
15
revised Examples of apparent patterns that eventually fail
edited body