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May
5
comment If $x$ and $y$ are rational numbers and $x^5+y^5=2x^2y^2,$ then $1-xy$ is a perfect square.
I think I do understand both your comments. Bill likes to welcome new users, and Patrick was right to mention that people who seek help should not just post a question without proper introduction. I think MSE should stop unregistered users to just post a question and vanish in thin air.
May
5
comment If $x$ and $y$ are rational numbers and $x^5+y^5=2x^2y^2,$ then $1-xy$ is a perfect square.
@PatrickDaSilva Thanks.
May
5
answered If $x$ and $y$ are rational numbers and $x^5+y^5=2x^2y^2,$ then $1-xy$ is a perfect square.
May
5
comment If $x$ and $y$ are rational numbers and $x^5+y^5=2x^2y^2,$ then $1-xy$ is a perfect square.
Did you at least find trivial ones, like $x=y=0$ then $1-xy=1=1^2$ ?
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)