# Search results

1. ### What to do with undeserved GOOD grades?

Hello. On fear of hijacking it, I didn't want to merge this with a similar thread earlier. Have you ever received an undeserved GOOD grade? Such as an A+ in a class, when you feel you should have received a B, or B-? I'm suspicious I'm getting better grades than I should. Yes, I am indeed...
2. ### Trying to Prove Uniform Convergence: Analysis II

Homework Statement I have a solution to the following problem. I feel it is somewhat questionable though If fn converges uniformly to f, i.e. fn\rightarrowf as n\rightarrow∞ and gn converges uniformly to g, i.e. gn\rightarrowf as n\rightarrow∞ , Prove that fngn...
3. ### Abstract Algebra: Parity of a Permutation

Homework Statement How do I determine the parity of a permutation? I think my reasoning may be faulty. By a theorem, an n-cycle is the product of (n-1) transpositions. For example, a 5 cycle can be written as 4 transpositions. Now say I have a permutation written in cycle notation: (1...
4. ### Intro Analysis: Proof that a limit = 0

This is an intro to analysis problem. I have already finished this proof (see attachment). I would like someone to check it for me. Its really short and easy. Thanks! -Abraham Tags: -Cauchy series -Infinite series -Limits
5. ### Help Me Understand the Archimedean Property

This isn't really hw. I need someone to explain a certain line in a proof: " b2 \leq \frac{1}{n} for all n in the natural numbers. This implies that b2 \leq 0 (a consequence of the Archimedean property). " I don't see how the Archimedean is applied in this context. This is my understanding...
6. ### Please check my (simple) proof. Skeptical of its simplicity

x,y are in R. Suppose x2+y2=0. Prove that x=0 and y=0. My proof: Suppose x\neq0, y\neq0. Then by the field axioms, both x2 and y2 are strictly positive, and so is their sum. This is a contradiction, since we supposed that their sum = 0. Thus, x=0, and y=0. This problem and proof...
7. ### PDEs solved with Separation of Vars., Method of Characteristics. What else is there?

I've taken a first semester course on PDEs. Basically all we learned was separation of variables and method of characteristics. I understand that there are transforms out there, such as laplace and fourier. However, it looks like there aren't many analytical ways of solving PDEs. Mind you, I'm...
8. ### Do derivatives introduce loss of solutions?

For example, if I want to show that there is no real # solution to x2 + 24x2 = -1 is it correct to show that d2/dx2( x4 + 24x2 ) = d2/dx2(-1) ---> 12x2+48 = 0 And since x^2 is >0 or =0, 12x2+48 ---> 0 + 48 \neq 0 Therefore, there is no real number solution to x2 + 24x2 = -1...
9. ### How many foreign languages can you take at once?

Sorry about the botched thread title. I meant it to read "How many foreign languages can you take at once." I'm wondering if there's a recommended limit for how much can be done at once? I'm not concerned with how much work it'll take, I'm concerned if there's a limit on my brain that I'm not...
10. ### 1st order linear diff eq. problem

Homework Statement Find the general solution of \frac{dy}{dt} = 2y +sin(2t) Homework Equations The general solution of a nonhomogeneous ode is the particular solution of the nonhomo plus the solution of the homogeneous ode.: y(t)= y_{p}(t)+y_{h}(t) The Attempt at a Solution...
11. ### What's the Reasoning behind the Maclaurin Series? How did Maclaurin discover it?

I've taken maths through calc 3. I understand the Maclaurin series represents a function f(x) as a power series: \sum(c_{n}x^{n}) But how the heck did Maclaurin figure out that the series \sum(c_{n}x^{n}) could represent f(x)? I mean, that's clearly not obvious from inspection. I want to...
12. ### Switching from engineering to mathematics

I'm switching from aerospace engineering to mathematics. I'll take any and all advice / suggestions / comments you might have Here are my reasons: 1.) I feel as if the aero program gives only the bare minimum math required to get through. I want to go on to grad school in Aero E, and...
13. ### Self Teaching: Linear Algebra?

I've taken maths up to calc III, and want to learn linear algebra over the summer. My school won't let me take more than 21 credits, which is what i'll be having for the next few semesters. I'm familiar with elementary row ops, gaussian elimination, least squares, but not much else. Is...
14. ### Bad idea? Taking Statics and Dynamics simulatneously

I'm considering this for summer at my local university (it doesn't have summer I or summer II options). Is it possible to do dynamics and statics all at once? Thanks!
15. ### Fortran Calling Gnuplot from FORTRAN

hello. I have a fortran code that has data points as output. How do I get fortran to plot these data points using gnuplot? Is there a way to call the external program from within fortran? I am using fortran95, gfortran compiler. I'm on a windows machine, but I'm connected remotely to...
16. ### Schools Do Graduate Schools Look at Extra Curiccular Involvement In Admissions?

Do Graduate Schools Look at "Extra Curiccular Involvement" In Admissions? I'm a freshman in the honors college, and we were told to make a resume that we'd like to have in four years when we graduate. I wrote that I'd have a B.S. in aerospace engineering with a minor in nondestructive...
17. ### Importance of GPA as an Engineer, (I'm not doing so well)

How important is gpa in college? How did it factor into you getting your current job? I don't find learning material difficult, but testing is killing me. I was so rushed these first few college exams. I understand the material very well. My style of working is carefully checking each...
18. ### Simple Model Rocket Project

We need to design a model rocket from scratch that is resistant to crosswinds and keep its trajectory withing a target zone. Does anyone know any methods to keep a model rocket stable in windy conditions? My idea was to make the rocket rather heavy, to resist the force of the wind. Would...
19. ### Which Integration Technique?

Homework Statement Solve: \int\sqrt{x^2-1}dx Homework Equations This is where I need help. What integration technique do I use? u-substitution? Integration by parts? None seem to work. As an added note, I've been trying to teach myself some calculus II work over the summer, so I...
20. ### Anyone know any good introductory philosophy books?

Anyone know any good introductory philosophy books? Unfortunately, all the intro to Philosophy courses at my university are closed until next year. I'm an engineering major, which practically has nothing to do with this. However, I find myself highly interested, or at least intrigued, by...
21. ### A question for anyone who does any research

I'll be an AerE freshman this fall, and I was amazed at my university library's stacks of journals. The peer-reviewed journals seem to have so many articles and details, that it seems as though someone has already done some research on just about everything. So for anyone who is a researcher, do...
22. ### Variable Change in Basic Integration

Could someone please explain to me how to do basic integration using the change variable method? I understand how to find "u" in the integrand, and then find du/dx, but I don't really know what's going on after that. For example: \int \sqrt{ln(x)}/x u= ln(x), right? and du/dx = 1/x...
23. ### Coefficient of Friction and Normal Force

I know that the force of friction is the (coefficient of friction) x (normal force). My question is, why isn't area involved? That is, why wouldn't a larger surface have more friction than a smaller surface, if the normal force is the same? PS: Sorry, just in case this is in the wrong section
24. ### Aerospace Engineer

I know there's a similar thread on mechanical engineers, but whats a typical day in the life of an aerospace engineer like?
25. ### Torque on a Turbine, Air Breathing Rocket Engine

Hi All, I'm a junior in HS. I have a research project due this semester for Physics B (first year introductory college physics). Last semester I did some research on boundary layers, friction loss in pipes. This semester I've decided to do some investigation on air breathing rocket...