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bodacydo
  • Member for 12 years, 6 months
  • Last seen more than 5 years ago
  • Washington, DC
51 votes
14 answers
18k views

Why is it that if I count years from 2011 to 2014 as intervals I get 3 years, but if I count each year separately I get 4 years?

51 votes
8 answers
184k views

Taylor series for $\sqrt{x}$?

50 votes
6 answers
6k views

We all use mathematical induction to prove results, but is there a proof of mathematical induction itself?

36 votes
9 answers
75k views

Can there be a function that's even and odd at the same time?

25 votes
8 answers
5k views

Google Interview Question about a town where if a couple has a girl born, they can't have more children... [duplicate]

25 votes
2 answers
6k views

What does "dual" mean exactly in mathematics?

22 votes
6 answers
8k views

Why is predicate "all" as in all(SET) true if the SET is empty?

18 votes
6 answers
19k views

What does $200\%$ faster mean? (How can something be more than $100\%$ faster?)

12 votes
5 answers
938 views

Can anyone explain why $a^{b^c} = a^{(b^c)} \neq (a^b)^c = a^{(bc)}$

10 votes
1 answer
694 views

If $dx/dy =\sin(x)$ then is $dy/dx = 1/\sin(x)$?

9 votes
2 answers
2k views

Is there a polynomial $p(x)$ with integer coefficients, such that $p(a)=p(b)=p(c)=p(d)=4$ and $p(e) = 10$?

9 votes
5 answers
29k views

Is it true that a 3rd order polynomial must have at least one real root?

6 votes
3 answers
2k views

What are your favorite integration tricks?

6 votes
4 answers
1k views

How to calculate what percentage of 228 is 199?

5 votes
6 answers
14k views

Can there be a month with 6 Mondays? (or 6 of any other days?)

4 votes
6 answers
583 views

Why doesn't $26\times 24 = 25\times 25?$ (I remove and $+1$ from both numbers) [closed]

4 votes
2 answers
178 views

How to solve this limit $\lim_{n\to\infty} ((\frac{1}{\sqrt{n^2+1}}) + \cdots + (\frac{1}{\sqrt{n^2+n}}))$

4 votes
1 answer
164 views

Suppose I've an equation $1/x = 5$, then is it the same as an equation $5x=1$?

4 votes
1 answer
63 views

Totally puzzled by calculating distance I'd be behind Usain Bolt if I competed with him

4 votes
2 answers
1k views

Another question about $x_0$ in the Taylor series

3 votes
3 answers
2k views

How to plot $r^2 = 36\cos(2\phi)$ in Cartesian coordinates?

3 votes
1 answer
220 views

Who determines if a mathematical proof is valid? [closed]

3 votes
2 answers
412 views

How to calculate (predict) how much I will be paid in 30 days if I know how much I was paid in the first 9?

3 votes
0 answers
407 views

When solving a big Rubik cube (100x100x100), do you reduce the solution to like 50x50x50, and then 25x25x25, and then like 10x10x10 and then 3x3x3?

2 votes
1 answer
174 views

How to solve infinite series $\sum_{n=0}^\infty\frac{n}{2^{(n+1)}}$? [duplicate]

2 votes
2 answers
163 views

If my salary grew from \$1,200 a month to \$1,300 a month, did I get \$100/\$1,200 = 8.3 % increase or \$100/\$1,300 = 7.7 % increase?

1 vote
2 answers
569 views

Is it possible to have such date and day combination that doesn't occur on any year ever?

1 vote
1 answer
58 views

In what cases the "rule" (a^b)^c=a^(bc) doesn't necessarily hold when a<0?

1 vote
3 answers
361 views

Why does the determinant $D$, have to be $0$ for equation to have a solution?

1 vote
1 answer
472 views

How to solve a $\lim_{x\to 0}\frac{\sqrt{1-\cos2x}}{x}$?