Emanuele Paolini
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 Oct22 revised Determinant value of $2 \times 2$ matrices added 78 characters in body Oct22 revised Determinant value of $2 \times 2$ matrices added 78 characters in body Oct22 revised Determinant value of $2 \times 2$ matrices added 10 characters in body Oct22 answered Determinant value of $2 \times 2$ matrices Oct22 comment There are 10 sticks of length 1,..,10. How many triangles can be formed Can triangles overlap each other? Do the intersections of sticks count as vertices? Oct22 comment There are 10 sticks of length 1,..,10. How many triangles can be formed I cannot get more than 4, and for 4 only 9 sticks are enough. Oct22 revised Dividing by 2 numbers at once, what is the answer? added 4 characters in body Oct22 revised Dividing by 2 numbers at once, what is the answer? added 246 characters in body Oct22 revised Dividing by 2 numbers at once, what is the answer? added 246 characters in body Oct22 revised Dividing by 2 numbers at once, what is the answer? added 246 characters in body Oct22 answered Dividing by 2 numbers at once, what is the answer? Oct22 comment Dividing by 2 numbers at once, what is the answer? While sums and moltiplications associate on the left, it is a good convention that powers associate to the right: A^B^C = A^(B^C). This because $(A^B)^C$ can be written anyway without parenthesis as $A^{BC}$. Python (and maybe other programming languages) agrees with this convention. Oct22 answered Find absolute maximum and minimum with domain Oct22 revised Find absolute maximum and minimum with domain revert and correct previous fix Oct20 answered Definite method for finding the intersection of two cartesian lines in 3D. Oct20 answered What does the nullity of T have to do with if it's isomorphic or not? Oct20 revised Can a convex polygon inside a square with edge length 1 have a perimeter > 4? added 11 characters in body Oct14 comment Is value of $\pi = 4$? I don't think this answers the question. The OP has correctly computed the length of the staircase and, apparently, he knows that $\pi \neq 4$. So he knows the reasoning is wrong (or at least contradictory) but he is asking which step fails. Oct11 revised In high school statistics, why does it seem like equations come out of the sky added 9 characters in body Oct9 comment If $f$ is an increasing function defined on $[a,b]$ . Then, $f$ has countable number of discontinuities Points of continuity must only be searched into the domain of the function, since the definition of continuity requires the value of the function to be computed in the point. If you decide that a function is not continuous where it is not defined, then the function $f(x) = \sqrt(x)$ would be discontinuous for every $x<0$ which is a not-countable set.