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2d
awarded  Student
Oct
22
awarded  Tumbleweed
Oct
22
comment How to find maximum of an inverse of a matrix?
@SaeedAref: Note that $H^{-1}=\frac{1}{\det H}H^*$
Oct
21
comment Improper integral : $\int_0^{+\infty}\frac{x\sin x}{x^2+1}$
I think you miss a "-" in front of $\lim_{a\rightarrow1}$.
Oct
21
comment Evaluate integral: $\int_0^{+\infty}\frac{\cos{bx}-\cos{ax}}{x}dx$
The last step should be $\ln\frac{a}{b}$.
Oct
21
comment How to find maximum of an inverse of a matrix?
Is there any other assumptions on $H$, such as $\det H$?
Oct
21
answered Evaluate integral: $\int_0^{+\infty}\frac{\cos{bx}-\cos{ax}}{x}dx$
Oct
21
answered Proof of $\arcsin x \le 2\arctan x$?
Oct
21
comment show that this polynomial can't multiple root occurring more $n-1$ times
@karvens: Yes, you are right, thanks very much, I haven't note about that and have edited yet.
Oct
21
revised show that this polynomial can't multiple root occurring more $n-1$ times
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Oct
21
answered If $f'(x)=f(x)+\int_{0}^{1}f(x)\,dx$ and $f(0) = 1,\,$ then what is the value of $\, \int_0^1 f(x)\,dx=$?
Oct
21
revised show that this polynomial can't multiple root occurring more $n-1$ times
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Oct
21
answered Showing the divergence of the series where $a_1 = 2$ and $a_{n+1} = \frac{5n+1}{4n+3}a_n$.
Oct
21
comment How do I do this double integral (change of variable)
Note that $(x^2+y^2)^2=(x^2-y^2)^2+4(xy)^2$
Oct
21
answered show that this polynomial can't multiple root occurring more $n-1$ times
Oct
20
revised Solve differential equation, $x'=x^2-2t^{-2}$
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Oct
20
revised Solve differential equation, $x'=x^2-2t^{-2}$
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Oct
20
answered Solve differential equation, $x'=x^2-2t^{-2}$
Oct
20
revised Solve $2xdy+(x^2y^4+1)y dx=0$
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Oct
20
answered Solve $2xdy+(x^2y^4+1)y dx=0$