Reputation
1,612
Next privilege 2,000 Rep.
Edit questions and answers
Badges
4 11
Newest
 Custodian
Impact
~19k people reached

Aug
23
comment Function of single variable $f(x)$, $f(x+y)=f(xy)$ and the exponential.
Two hints, which someone will probably write as an answer before I've finished. 1. Set $x = y= 0$ in the equation $f$ satisfies. That tells you something about $f(0)$. 2. Use the definition of the derivative as the limit of $(f(x+h) - f(x))/h$ as $h$ approaches $0$.
Aug
21
comment Calculate the Height of Christmas
+1 for noting the importance of refraction.
Aug
18
comment A Stupid Question About $O(3)$ Group
I tell my students there's no such thing as a stupid question. Perhaps you're puzzled by something that ought to be easy - but for you it isn't, so ask (as you did). That's not stupid.
Aug
16
comment If $3x^2 -2x+7=0$ then $(x-\frac{1}{3})^2 =$?
You can learn from the two different kinds of solutions below. One strategy is to complete the square and hope to be lucky. That would occur to you if you had some experience knowing when and how to complete the square. The other is to start by multiplying out the sought for square, hoping to find something useful. That's a good strategy if nothing else comes to mind.
Aug
16
comment Can we make a subgroup of a group by selecting exactly one element from each distinct left cosets of a subgroup of the given group?
You can't for the even integers as a subgroup of the integers. Are you asking if this is ever possible?
Aug
14
comment Formal proof of a simple fact, namely that $S$ has even cardinality if certain pairs could idenitifed
I agree that formally it's equivalent. In that sense there's no harm in it. But to my taste the direct proof is cleaner. Since not all proofs by contradiction are constructive and students can't appreciate the distinction I want them to look for direct proofs when possible.
Aug
14
comment Formal proof of a simple fact, namely that $S$ has even cardinality if certain pairs could idenitifed
With this idea you can prove the theorem directly. You don't need the extra baggage of a proof by contradiction.
Aug
2
comment What is the significance to our number and degrees systems?
Duplicate of duplicate? math.stackexchange.com/questions/340467/… and math.stackexchange.com/questions/142735/…. Found these with a search for why 360 degrees
Jul
31
comment Is ideal an “anti-field”?
+1 for addressing the intuition behind the OPs question.
Jul
27
comment Find bounded function satisfying f(0)=0, f'(0)=0, and bounded first and second derivatives
Trig is a good place to start. How about $\sin^2{x}$?
Jul
26
comment explanation of notation in programming problem
See csl.mtu.edu/cs4321/www/Lectures/….
Jul
25
comment explanation of notation in programming problem
The answers below all address your notation question. None discusses it as a programming question. Computing those factorials is not a good way to compute the final answer. There are lots of others. A course in data structures and algorithms will discuss the pros and cons.
Jul
25
awarded  Custodian
Jul
25
reviewed Approve Explaining elementary arithmetic in terms of group theory
Jul
24
revised Explaining elementary arithmetic in terms of group theory
edited body
Jul
24
answered Explaining elementary arithmetic in terms of group theory
Jul
22
comment Definitions for complex numbers
Related: math.stackexchange.com/questions/1364439/…
Jul
21
comment If $\frac{a+b}{b+c}=\frac{c+d}{d+a}$ then..
Question. Are you sure you copied (B) correctly from your source?
Jul
19
answered boundedness theorem for continuous functions question
Jul
18
comment Tangent to the curve
Your answer is correct (as the answers show). If you drew a picture for yourself you might have had more confidence in it.