Recent content by thecaptain90

Thanks, didn't think of doing this.

Hi, I'm stuck on a problem because I don't know how to calculate this series: Ʃ(2^n * x^n), n starts from 0 to infinity. How can I calculate this? Do I have to transform it into something else where I know the outcome of the Σ like we do with the geometric functions?

Thanks for clearing these things up.

So I've got a calculus test in a week, and I'm studying for it but I can't understand some examples our professor has given us. So, he says: 1) A = { x\in ℝ: (x-a)(x-b)(x-c) < 0 } , a<b<c. Find the supA and infA. In the solution of his example he says. It is easy to see that A =...

Hi. My problem is that even though I can find the Fourier series, its coefficients etc. I have trouble determining the period of equation. For example let's say we have f(t) = t, t \in [-pi,pi]. I thought that the period was 2pi but in the solution it says that the period is pi. This isn't the...

Yep this is my fault it says that I should show if U is a subspace of R3. I'm a student in a greek school so you probably won't know the book I'm using it is only available in greek. Thanks for the help. I'll try to solve some exercises and post some questions if I get stuck.

Sorry for not answering for quite some time. The exercise I posted is from a book maybe it has a mistake as rasmhop said. There is another one which I don't know how to solve: U={(x,y,z) \in R3 | xyz = 1} I have to show that U is a subspace of R3. What should I do? According to my book it says...

Hi, I'm new to linear algebra. I'm pretty good at doing exercises with matrices and stuff but even though I've been looking in different books, looking all over the internet I can't get into vector spaces and subspaces. It seems like the books have some very elementary and simple examples and...