Recent content by Nidhogg

D'oh! I didn't even realize that it was that simple. I was overthinking it. Obviously, the two ##\delta## values are ##\sqrt{0.5}## and ##\sqrt{1.5}##, which ##\approx## 0.70 and 1.22 respectively. Plug either of these into the original function, subtract one, and take the absolute value, and...

Homework Statement "Use the given graph of f(x) = x^2 to find a number delta such that..." Homework Equations If ##([\lim_{x \rightarrow a} f(x)] - L)## then there exists an ##\epsilon## such that ##[0 < |x - a| < \delta] \Rightarrow [|f(x) - L| < \epsilon]##. Here, f(x) and ##\epsilon##...

Okay, I can see that \lim_{x \rightarrow \infty} e^{-7x} = 0 Which means that the limit as a whole should be 0, if it's not that case that the limit DNE. In that case, can I use the Squeeze Theorem like this? [-1 \leq \cos x \leq 1] \Rightarrow [-e^{-7x} \leq e^{-7x} cos x \leq e^{-7x}]...

(sorry the thread title is wrong - can a mod please change it to "Limit of e^-7x cos x?") 1. Homework Statement Find the following: \lim_{x \rightarrow \infty} e^{-7x} \cos x Homework Equations I know that [ \lim_{x \rightarrow a} f(x)g(x) ] = [ \lim_{x \rightarrow a} f(x) ] \cdot [ \lim_{x...

Wow, thanks for all your help, Ciubba! I'll be studying some of the more complex delta-epsilon proofs with a friend this evening and your post will definitely be referenced for that.

Ciubba: I'm not sure, but I think I'm getting closer to grasping this. We know now that when δ=ϵ/3, the limit inequality of |3x + 1 - 7| < ϵ holds. So what else do I have to do? Do I have to prove that there exists a δ such that δ=ϵ/3 for all ϵ? Isn't that necessarily true anyway since ϵ is...

So according to what RUber said, I have ## |x - 2| < \delta ## and ## 3|x - 2| < \epsilon##. I need to find from these two that such a delta exists for every epsilon, and I do this by putting together an inequality that relates delta and epsilon? So, to take another whack at it I have...

ciubba: D'oh, that was a typo! I fixed it. RUber: Thanks, man. I'll work on it a little more tonight.

I'm looking for a good, general explanation of how to do delta/epsilon proofs. I've searched all over the web but this stuff is just really confusing. Let me start with a problem, show my attempt at a solution, and then maybe you guys can explain it in a way that will make sense to me...

Thanks to analogdesign and Choppy for your advice! I think I'm leaning in the direction of CS now, just from what both of you have said. I didn't know about the residency thing with medical physics. I think I'll stay away from that now. I'm 25 already and staring down another 3 years of...

Hello! I'm currently a junior at Miami University in Ohio. I just recently added physics to my list of majors (my other major is philosophy). A little background on me: my interest in physics began a few years ago, during a break from university that I took between the ages of 20 and 24 (I'm 25...

So, I'm currently in the process of getting my B.A. in physics from Miami University. Not exactly a top-tier school, but not a throwaway school, either. I should be able to graduate with a GPA between 3.2 and 3.4, and I tend to test very well, so I'm not worried about my GRE scores. Anyway, my...