Recent content by Tala.S

I have to examine whether this sequence Xn = ln(n^2+1) - ln(n) converges or diverges. My attempt at a solution: Xn = ln(n^2+1) - ln(n) = ln((n^2+1)/n) = ln(n+1/n) Xn → ∞ when n → ∞ So the sequence diverges. Can someone look at this and see whether the procedure...

Yes. Thank you jfgobin :)

since a>0, b>0, c>0 and \left( a-c\right )^2 > 0, the expression \left( a-c\right )^{2}+2ab+b^2+2bc must be positive.

Oh no of course it can't !

Yes it can become negative.

Not really :S I can't see how I can use a binomial formula ? Is it something like this (a-c)^2=-r, r\inℝ ?

well I see the equation a^2+c^2+2ac but I'm not sure why or how to use the binomial formula ?

x has to be negative ? The expression can be complex if 2ac>b^2+2bc+c^2+a^2+2ab ? I can't really see what the term should look like ?

Hi I'm trying to figure out whether this expression √(a^2+2ab-2ac+b^2+2bc+c^2) can be complex or not while a>0, b>0 and c>0. My answer would be no but I'm not sure.

Okay. Thank you :smile:

But what do you mean with best idea ? I can see that both parameterizations can work but how is one better than the other ?

Thank you voko.

The explanation was good. Thank you. I have one question concerning the parametrization of S. since z=h(x,y) wouldn't a possible parametrization of S be : r(u,v) = (v(6-u^2), u, 6-(6-u^2)*v-u^2) ?

I don't understand why you choose the boundaries for v to be that. And the last two lines...wasn't x = v(6-u^2) with the boundaries -√6 ≤ u ≤ √6. I'm a bit confused now :(

I hadn't thought about that one. But I'm curious what would the boundaries for v be in the other parameterization?