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bio website math.stackexchange.com/users/…
location Antarctica
age 78
visits member for 1 year, 9 months
seen Jan 31 at 5:07

Self-learning mathematics. Many thanks to those who make time to help others on the site.


May
27
comment Proving $\sum_{m=0}^M \binom{m+k}{k} = \binom{k+M+1}{k+1}$
Is there a typo in the second equation (first sum)? I believe $k$ should be indexed.
May
26
comment Finding the values of $z$ s.t. $\sum_{n=0}^{\infty} \left( \frac{z}{1+z} \right)^n$ is convergent
yeah, I got the same thing, but I just didn't express the final step like that. Does it matter though?
May
26
comment Finding the values of $z$ s.t. $\sum_{n=0}^{\infty} \left( \frac{z}{1+z} \right)^n$ is convergent
$z > 1-\bar{z}$?
May
17
comment Are there any series whose convergence is unknown?
Out of curiosity, what makes this a "joke" answer?
May
14
comment Finding asymptotes of exponential function and one-sided limit
@Mhenni Why are the first two terms of the taylor series expansion enough to find the asymptote? Certainly there are functions where the first two terms wouldn't suffice to give an accurate approximation.
May
14
comment What are the limits and asymptotes of $f(x)=x+\frac{1}{x}$?
@Garmen1778 I'm not sure if you were implying that there was a horizontal asymptote or not, but in case there's any ambiguity, there are no horizontal asymptotes.
May
12
comment Using $\gcd(a,b)$ to find gcd of other values $\gcd(a^2,b)$ and $\gcd(a^3,b)$
Why is $b = p^{50}m$?
May
3
comment Is there something faulty about this statement?
Yeah, but when they used $k$ in both, it reads that the $k$'s are going to be the same. Is this sort of thing standard notation?
May
3
comment Trig and algebra problem: Finding sides of a triangle
by expanding the whole thing on the RHS?
May
3
comment Trig and algebra problem: Finding sides of a triangle
I was able to get that, but I don't know what to do with it
May
2
comment Rudin or Apostol
@BrianM.Scott When you say Apostol covers more material, do you mean that he's just more explicit in his explanations or he covers all the topics and theorems that Rudin does, plus more?
Apr
26
comment Show that there is no rational number $r=m/n$ such that $r^3=3$
@EricNaslund Do you mean as long as $n\geq 2$ is an integer?
Apr
25
comment Show that there is no rational number $r=m/n$ such that $r^3=3$
@ThomasAndrews Does it make a difference that this is cubed root?
Apr
25
comment Proving a complex equality
So for the trivial case, you can't use the quotient you've set $z$ equal to?
Apr
23
comment Proving a complex equality
I'm aware of that answer, but I'm looking for an algebraic answer simply because that wouldn't come to me immediately. How did you see that it was an ellipse? I ask because it's not in the familiar form that you see in conic sections of calculus.
Apr
13
comment Finding a closed form expression for this sum
How do you know that the 2nd term is equal to $(1/\sqrt{1-4x})^2$?
Apr
13
comment Finding a closed form expression for this sum
@MarcvanLeeuwen How did you search for that? I didn't know how to search for it because there's no specific name or term associated with it. O.w. I'd just have to look through all the results one at a time.
Apr
11
comment Solving functional equation for generating function
But doesn't that change the value of the sum?
Apr
11
comment Solving functional equation for generating function
Yeah, I've been trying to figure out how to get the indices to start at $0$ all day. Why is it you can just start the the indices (in your hint) at $0$?
Apr
11
comment Simplifying Catalan number recurrence relation
@BrianM.Scott In the first half of your answer, how do you go from $1+x\sum_{n\ge 0}\sum_{k=0}^nC_kC_{n-k}x^n$ to $1+x\left(\sum_{n\ge 0}C_nx^n\right)^2$