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Sep
29
answered Using a function to order an integer's digits from least to greatest?
Sep
29
comment Using a function to order an integer's digits from least to greatest?
The function you describe is perfectly mathematical. Probably what you mean is if one can write such a function as a composition of "elementary" function (where elementary functions are the ones you see on a pocket calculator). In this sense the answer is probably not.
Sep
29
comment Counting numbers in a sequence - explain “Add 1 before you're done” rule
@psmears: ops :-D I removed my comment
Sep
28
comment Proving that the complex function $z^n$ is continuous
I think it is easier to prove that the product of continuous functions is continuous. The result then follows by induction.
Sep
27
comment Solving limits without using L'Hôpital's rule
Taylor at order 1 is simply the definition of derivative. L'Hospital theorem is much more than that...
Sep
26
revised What condition should an $m\times n$ matrix $A$ meet for $x\mapsto\|Ax\|$ to define a vector norm
added 13 characters in body
Sep
26
comment What condition should an $m\times n$ matrix $A$ meet for $x\mapsto\|Ax\|$ to define a vector norm
right, corrected!
Sep
26
answered What condition should an $m\times n$ matrix $A$ meet for $x\mapsto\|Ax\|$ to define a vector norm
Sep
26
comment Show that $ x\mapsto e^x$ is continuous.
See en.wikipedia.org/wiki/…
Sep
26
comment Is -2 is a root of the equation : $\sqrt {x^2 - 8} = \sqrt {3x + 2}$?
you are saying that sqrt(-4) = 2i. This is questionable, I have never seen such a definition.
Sep
26
comment Is -2 is a root of the equation : $\sqrt {x^2 - 8} = \sqrt {3x + 2}$?
Anyway the square root is not defined.
Sep
26
answered Set question, relations, equivalence classes
Sep
26
revised Set question, relations, equivalence classes
deleted 1 character in body
Sep
26
answered Is -2 is a root of the equation : $\sqrt {x^2 - 8} = \sqrt {3x + 2}$?
Sep
26
revised Is -2 is a root of the equation : $\sqrt {x^2 - 8} = \sqrt {3x + 2}$?
deleted 12 characters in body
Sep
25
revised Show that $ x\mapsto e^x$ is continuous.
added 26 characters in body
Sep
25
revised Show that $ x\mapsto e^x$ is continuous.
added 59 characters in body
Sep
25
comment Show that $ x\mapsto e^x$ is continuous.
right... I add it!
Sep
25
revised Solve the following equation. Check all proposed solutions.
edited tags
Sep
25
comment Can you fit every single permutation of a triangle inside a circle with all three points touching the edges of the circle
The statement is not clear. What are the permutations of a triangle? The circle is fixed?