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May
5
answered Funny identities
May
5
answered Integration: area enclosed by graph of $x^4 + y^4 = 1$
May
4
answered Why is fibonacci coding useful?
May
4
comment Statistics : Where did this degree of freedom formula for the T distribution come from?
Maybe stattrek.com/estimation/difference-in-means.aspx?tutorial=stat can help. Under the subsection titled "If you use a t score, you will need to compute degrees of freedom (DF)."
May
1
answered Absolute max for $f(x,y,z)=x^ay^bz^c$, with constraint $g(x,y,z)=x+y+z-1$
May
1
comment Integration of $\int_0^{\pi/2} \frac{1}{\tan^2(x)}dx $?
The integral does not converge $-\cot x -x$ from $0 $ to $\frac{\pi}{2}$
Apr
28
answered Approximating log of factorial
Apr
27
answered What is proxy graph?
Apr
26
comment How do you find all $n$ such that $\phi(n)|n$
@LHS That is correct, I just wanted to see if you could think further.
Apr
26
comment A book for self-study of matrix decompositions
Yes that is correct. Also if you want to try out some software packages, NIST's JAMA (math.nist.gov/javanumerics/jama) is one option you might consider.
Apr
26
answered A book for self-study of matrix decompositions
Apr
23
answered $\int_0^{2\pi}\sin\frac{x}{2}\cos^2\frac{x}{2}\,dx$
Apr
23
comment How do you find all $n$ such that $\phi(n)|n$
@LHS think about it. Can $n$ be prime? or Can $n$ be odd?
Apr
23
comment Find the sum of the roots of the equation?
@vikiii the sum of the roots is the absolute value of the coefficient of $x^9$ which is the absolute value of $1+ {10 \choose 1} (-10) = 1 - 100 = -99$ and that absolute value is $99$. For instance what is the sum of the roots of $(x-2)^2+(x-4)^2=0$? which is $2x^2-12x+20=2(x^2-6x+10)=0$. The sum of the roots is the absolute value of the coefficient of $x$ and that is 6.
Apr
23
comment What is $\lim\limits_{k \to 0}{f(k) = 2 + k^{\frac{3}{2}}\cos {\frac{1}{k^2}}}$
@mathstudent Arturo is right (listen to the master). The limit of $cos\left(\frac{1}{k^2}\right)$ does not exist. snipurl.com/236mdru
Apr
22
comment How to show that $91$ is a pseudoprime to the base $3$?
Oops! That was indeed a good catch (should have paid more attention)
Apr
22
awarded  Revival
Apr
21
answered How to find bits you need to represent one variable? How many integers( 16 or 32 bits) you need when programming the problem?
Apr
21
answered How to show that $91$ is a pseudoprime to the base $3$?
Apr
21
awarded  Necromancer