2,925 reputation
1815
bio website
location Houston, TX
age 31
visits member for 4 years, 3 months
seen yesterday

Sep
12
comment In plain language, what's the significance of a field?
@Hal: Not always. Another thing that would keep a field from having less/greater than is the numbers being conceived of two-dimensionally. Think of $\mathbb{C}$.
Jul
25
comment inverse trigonometric equation $\displaystyle \tan^{-1}{x}+\cot^{-1}{x}=\frac{\pi}{2}$
Hint: $\cot x = \tan(\frac{\pi}{2} - x)$.
Jul
16
comment Are all existence proofs by contradiction?
Related: math.stackexchange.com/questions/427078/is-0-a-field
Jul
8
comment Calculate $\sum_{k=1}^n \frac 1 {(k+1)(k+2)}$
@Elimination beat you to it by 22 seconds.
Jul
4
comment How to distinguish walking on a sphere or on a torus?
@dotancohen: Even if they could look up, people living on the outer parts of Planet Doughnut wouldn't have a view of the hole.
Apr
20
comment Kid's homework: 4 equations 5 unknowns? Going crazy!
@metacompactness: Not necessarily. For example, there could be half-siblings on this trip, with 1 father and 2 mothers. Or cases where one parent is unable to attend.
Apr
5
comment Derivatives of exponential functions
There's no $x$ in your function. Did you mean dt instead of dx?
Apr
5
comment How can a piece of A4 paper be folded in exactly three equal parts?
It would be interesting to see an answer that relies on the $\sqrt{2}:1$ ratio of ISO paper sizes.
Mar
29
comment Why is there a different button for 'minus' and 'negative' on a calculator?
@Rahul: Based on your comment, I assume that you have an RPN calculator. However, I've also seen distinct - and buttons on infix-notation calculators like the TI-8x series, on which there's no obvious need to distinguish them.
Mar
29
comment Why is there a different button for 'minus' and 'negative' on a calculator?
This doesn't really answer the question. Although unary and binary minus are indeed distinct operations, a lot of programming languages, spreadsheet programs, etc., do manage to use the same symbol - for both of them.
Mar
29
comment Can a piece of A4 paper be folded so that it's thick enough to reach the moon?
Assuming a typical 0.1 mm thickness, how large would a sheet of paper need to be so that it could be folded 42 times?
Mar
28
comment Can a piece of A4 paper be folded so that it's thick enough to reach the moon?
1L << 42 is faster than calling a function ;-)
Mar
28
comment Can a piece of A4 paper be folded so that it's thick enough to reach the moon?
Just to verify, I measured a package of 500 sheets of paper, and it was about 5 cm thick. So, 0.1 mm per sheet is a good estimate.
Mar
28
comment Can a piece of A4 paper be folded so that it's thick enough to reach the moon?
A piece of A4 paper cut in half 42 consecutive times would be A46.
Mar
28
comment Why is the $O$ (zero) matrix important?
Do you understand why the number 0 is important?
Mar
8
comment What is exponentiation?
Related (almost a duplicate) question: math.stackexchange.com/questions/132703/…
Mar
8
comment Do we need to formally teach the Greek Alphabet?
You're not really “out of luck” if you don't know the key; you can just do a linear search through the dictionary's values until you find what you're looking for. Of course, this takes O(n) rather than O(1) time.
Feb
18
comment Fractional Power Interpretation
Duplicate of math.stackexchange.com/questions/132703/…
Jan
22
comment How do I convince my students that the choice of variable of integration is irrelevant?
If you want to mess with students' heads, use $e$ as a variable of integration.
Jan
21
comment If $5 \times 12 = 104$, how much is $10 \times 11$?
It also works if the base is equal to 2.