Javier Badia

2,563 reputation

1522

bio	website
	location	Buenos Aires, Argentina
	age	20
visits	member for	2 years, 7 months
	seen	7 hours ago
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(my about me is currently blank)

	2,563 reputation	bio	website		visits	member for	2 years, 7 months
1522 badges		location	Buenos Aires, Argentina		seen	7 hours ago

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Apr 14	comment	How do you find the limit of $\frac{4x^4 + 5y^4}{x^2 + y^2}$? @PeterTamaroff: No, there's a norm squared in the denominator.
Apr 13	comment	Why vector calculus seems inconsistent and vague Do you have a similar interpretation for the curl? That was pretty awesome.
Apr 13	comment	Let $f:[a,b]\to\mathbb R$ be Riemann integrable and $f>0$. Prove that $\int_a^bf>0$. (No Measure theory) I'm guessing this is the part of measure theory that the question specifically asks shouldn't be used.
Apr 13	answered	Doubt on rational and real numbers
Apr 13	comment	Doubt on rational and real numbers Then by that logic, there are also a lot of rational numbers. I'm saying that yoru statement doesn't contain a lot of information particular to the irrationals.
Apr 13	comment	Doubt on rational and real numbers $\mathbb{Q}$ is also dense in $\mathbb{R}$.
Apr 12	revised	How to differentiate integrals with variable limits? deleted 1 characters in body; edited title
Apr 11	comment	How to solve $\sinh x = x$? You can use calculus to prove the last equation has zero as its only solution.
Apr 11	comment	Differentiate the equation: $y = x{(1 + 3x)^5}$ using the product rule @Assad: It's not that you made a mistake in the math. You simply copied wrong from the book.
Apr 11	comment	Differentiate the equation: $y = x{(1 + 3x)^5}$ using the product rule Nitpick: you're not solving, you're differentiating. There's no unkown to find here.
Apr 11	comment	MacLaurin series of $\ln(1-x^2)$ @user51462: As far as I can tell, it's $\ln(1-x^2) = -\sum_{n=1}^{\infty} \frac{x^{2n}}{n}$. How did you get that? You should know the series for $\frac{1}{1-x}$, get $\frac{1}{1+x}$ from that, then get $\ln(1+x)$ from that, and finally get $\ln(1-x^2)$ from that.
Apr 10	comment	MacLaurin series of $\ln(1-x^2)$ You think? What's the series for $\ln(1+x)$?
Apr 10	comment	Finding a parameter of a function It says right there: $P$ (and therefore $f$) has only one root in that case.
Apr 10	answered	MacLaurin series of $\ln(1-x^2)$
Apr 10	comment	Finding a parameter of a function The question asks for what values of $a$ there's only one root. Your answer seems to imply (sorry if I misinterpreted!) that except for $a = -\frac32$, every other value will work.
Apr 10	comment	Finding a parameter of a function The problem is that if $a \lt -15$ there are three roots, so those values don't work.
Apr 10	answered	Finding a parameter of a function
Apr 10	comment	Finding a parameter of a function Does the question say whether there is only one value of $a$, or are you supposed to determine how many there are and find them?
Apr 10	comment	Finding a parameter of a function You could in principle use the cubic formula.
Apr 10	comment	Let $E \subset ℝ^n$ open and $f:E→ℝ^m$. Then is $f$ cont. diffb. on $E$ $⇔$ all the partial derivatives $D_jf_i$ exists on $E$ and are cont. on $E$. @PeterTamaroff: Oh, that makes sense.