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I was born to answer lhfs.


May
26
comment Proving that either $2^n-1 $ or $ 2^n+1$ is not prime
Why are you not using \rm for variables today?
May
26
comment How to prove $\sum\limits_{n=1}^{\infty}\frac{\sin n}n=\frac{\pi-1}{2}$
That, my friend, is an epic observation. :-)
May
26
accepted What is $-i$ exactly?
May
25
comment Algebra Equation with equals on left hand side
@amWhy Just saying, but some people who have started with algebra-precalculus may not understand what a relation is, let alone a symmetric relation. I think you should include a link which explains equivalence in classical logic as well as relations. Thanks :-)
May
24
comment How do you define definition symbol :=?
:= := :=, if you know what I mean. ;-)
May
24
comment What is $-i$ exactly?
@AdrianPetrescu but 1 does have a sign, which is +, so we can use - to negate it. Here, I first focus on how -i cannot exist and then I say that even if it does, what differences are there between the two?
May
23
comment How to show $x^4 - 1296 = (x^3-6x^2+36x-216)(x+6)$
I agree. :-) ${}$
May
23
comment How to show $x^4 - 1296 = (x^3-6x^2+36x-216)(x+6)$
(Mostly known as the synthetic division.)
May
23
comment How to show $x^4 - 1296 = (x^3-6x^2+36x-216)(x+6)$
Uh, actually I am saying that you wrote $a^4 - b^4 = a^3 + a^2 b + ab^2 + b^3$. It should be $a^4 - b^4 = (a - b)(a^3 + a^2 b + ab^2 + b^3)$
May
23
comment How to show $x^4 - 1296 = (x^3-6x^2+36x-216)(x+6)$
$a^4 - b^4 = (a - b)(a^3 + a^2 b + ab^2 + b^3)$...
May
23
comment How to show $x^4 - 1296 = (x^3-6x^2+36x-216)(x+6)$
Note that the factorization is easily derivable by the Factor Theorem.
May
23
answered How to show $x^4 - 1296 = (x^3-6x^2+36x-216)(x+6)$
May
22
comment Choice of numbers in calculating $\lim_{x\rightarrow 0}\frac{e^{2x}-1}{\sin 3x}$
I think what lab said suffices.
May
21
awarded  Good Question
May
21
revised Determine the inverse function of $f(x)=3^{x-1}-2$
added 39 characters in body
May
21
answered Determine the inverse function of $f(x)=3^{x-1}-2$
May
21
comment The sum of irrationals is irrational?
@user17762 And there's a populist badge for ya.
May
20
revised Given $x,y,z\geq0$ and $x^2+y^2+z^2+x+2y+3z=13/4$. Find the minimum of $x+y+z$.
edited >= to ge symbol
May
20
comment Why is 987654321/123456789 = 8.0000000729?
Ah, gotcha. Nice answer.
May
20
comment Why is 987654321/123456789 = 8.0000000729?
Is it just me who is too stupid to understand what the pattern is?