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awarded  Popular Question
7h
comment Record-holding mathematical proofs
How about the abc conjecture?
8h
comment Prove that the sum of the vectors from the centre to the vertices of a regular hexagon is 0
The proof isn't one line, but you can group the vertices by pairs and observe that each pair has zero sum.
1d
comment Only two groups of order $10$: $C_{10}$ and $D_{10}$
This is a seriously underrated answer! Such insight would have been quite useful when I was studying algebra.
Jan
30
comment number of combinations in a set
Since there are $9$ elements in your set, there are $2^9$ elements in the power set. However, you might want to exclude the set of size zero (the "empty set"), so so there are $2^9 - 1$ subsets.
Jan
30
comment number of combinations in a set
en.wikipedia.org/wiki/Power_set
Jan
29
comment Prove the following simple exponentiation equality.
(+1) for the first sentence. Context was definitely not clear initially!
Jan
29
comment Prove the following simple exponentiation equality.
No, but if you can get $b^y > d$, then just set $y = -x$ and $c = 1/d$
Jan
29
comment equation of straight lines through a point which divide the circumference of a circle in the ratio $2:1$
(Though it should probable be mentioned that I only needed one line...)
Jan
29
comment equation of straight lines through a point which divide the circumference of a circle in the ratio $2:1$
I did it! Neat problem, thanks.
Jan
29
comment Prove the following simple exponentiation equality.
You can probably use the principles behind the logarithm without invoking the function.
Jan
23
comment World Problem Math Algebra Fraction
This would be my interpretation, assuming the string "1 2" in the OP is actually just $12$
Jan
23
comment World Problem Math Algebra Fraction
Why did you write "1 2"? Is it 12?
Jan
22
comment Can we say $x=4$ is a Point of Inflexion
Are you sure the sign of the second derivative changes?
Jan
22
comment How, if at all, does pure mathematics benefit from $2^{74207281}-1$ being prime?
+1 for a good answer, and a blast from the (MMF) past!
Jan
20
comment How to write a definition of less than $<$?
There's nothing terribly wrong with the word - it just seemed funny that a word with such finality would be used to demonstrate $3 < 5$, a fact almost irrelevant to the task at hand.
Jan
19
comment How to write a definition of less than $<$?
"finally" - ???
Jan
19
comment How to write a definition of less than $<$?
No. You are using the < in its own definition!
Jan
19
comment Why can't you have more turning points than the degree?
"There are four [real] roots, so the degree is at least $4$..."
Jan
19
comment GRE Algebra answer is wrong
@user247327: The original post said no such thing: math.stackexchange.com/revisions/1617611/1