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Sep
21
comment Free resources to start learning Discrete Mathematics
See the suggestions given in math.stackexchange.com/questions/1533/… and math.stackexchange.com/questions/350/….
Sep
21
comment Indirect proof that sum of first n even numbers is $n^2 + n$
The picture here may give you some ideas.
Sep
20
revised How do I prove that $x^TAy = y^TAx$ if A is symmetric?
texed equation, put question in title, add homework tag per question body
Sep
17
revised Given a collection of items, how many ordered subsets can I make?
texed sum, better title, tag -permutations +combinatorics
Sep
17
comment Given a collection of items, how many ordered subsets can I make?
@AvatarOfChronos: To add on to Moron's comment, you can right-click any existing formulas and click 'show source' to see how to write something similar, or see your edited question. For more details, see the proposed faq.
Sep
17
revised How many 7-digit even numbers less than 3000000 can be formed using all the digits 1,2,2,3,5,5,6?
tag -permutations +combinatorics
Sep
17
revised Wedge product and cross product - any difference?
removed unhelpful tag [vector], added tag [terminology] (maybe should be notation?)
Sep
17
revised What are the names of graphs with 2 in/outbound edges?
added [terminology] tag
Sep
16
comment Optimal sample size?
See the proposed faq on meta for some pointers on how to type math here.
Sep
16
revised Optimal sample size?
forgot the $; added 1 characters in body
Sep
16
revised Counting placing items in bins according to boolean restrictions
added text of moron's answer
Sep
16
comment What is the meaning of the double turnstile symbol ($\models$)?
TeX fixed - see meta.math.stackexchange.com/questions/692/…
Sep
16
revised If $x$ is a $p$-value, what do we call $x\cdot (1-x)$?
made title specific, tag [name] -> [terminology]
Sep
16
revised What is the meaning of the double turnstile symbol ($\models$)?
unsupported \implies and \vDash changed to \Rightarrow and \models
Sep
16
answered If $x$ is a $p$-value, what do we call $x\cdot (1-x)$?
Sep
15
comment Is this proof of $a^{1/2}$ being either integer or irrational circular/incorrect?
Closing for 3 votes + Isaac♦ and myself
Sep
15
comment fast and reliable method for testing invertibility of Hermitian Toeplitz matrix
See also Mathworld and Wikipedia's descriptions of the condition number. If you are using some linear algebra library, note that many calculate the reciprocal of the condition number by default.
Sep
15
revised Is this proof of $a^{1/2}$ being either integer or irrational circular/incorrect?
nice-ified title. "bogus" quote now only remains in question body
Sep
15
comment Direct proof that f(x)=x sin(1/x) does not satisfy Lusin N condition
@Myke: I believe \sout requires the ulem package, which is not installed. The html way is to use <s>text</s> (or <strike>text</strike>)
Sep
15
comment How can I pack $45-45-90$ triangles inside an arbitrary shape ?
What Moron stopped short of saying outright is that you can lay your image on top of a square grid, then shade in all squares that are part of the shape (filled or >half filled, for small enough squares it doesn't matter), and bisect them to get the triangles you want. I don't write this as an answer because although it answers your question as written, I think it also suggests some clarifying edits you may wish to make to bring it closer to your 'real' question.