Recent content by adamwitt

Yes, that makes much more sense. But I've been given r = x^2 + y^2... must have been a mistake in the question itself. Thanks for your help guys.

Ok, so my understanding of Jacobian Matrix is how you have described. I've got no idea how to post matrices etc on here so my descriptions above may have been a bit off, but I'll try suss it out for this post... Ok so, my understanding is fine all the way up until you talk about the Jacobian...

Hi, I need some help understanding the solution to a problem. Equations: x = r.cos(θ) y = r.sin(θ) r = x2 + y2 theta = arctan(y/x)Question: Determine the Jacobian Matrix for (x,y)T and for (r, θ)T SOLUTION: I understand and can compute by myself the Jacobian for (x,y)T, but the solution to...

Homework Statement After extensive investigation, a researcher has found that the mean travel time for mice through one particular maze is 29.0 seconds. She believes that the mice will move faster through the maze when subjected to a loud noise. In order to assess this, the researcher has...

Ok I gave it a crack using basic expansion, lemmy know if I am close :) E(X2(3Y-1)) E(3X2Y-X2) 3E(X2Y)-E(X2) Then from there its a fairly simple process of taking the integrals of the various functions. In my examples case the marginal prob dens functions are only defined for certain values so...

Expected Values... E(X^2(3Y-1)) Homework Statement What is the Expected Value of E(X2(3Y-1)) Homework Equations Properties of Expected Values. E(X+c) = E(X) + c E(X+Y) = E(X) + E(Y) The Attempt at a Solution I tried googling for a few of the properties I could use but I'm...

Why do I care what the laplace of H(t-a) is? How do I use e^(-as).L{1} to find H(t-a) ? The Laplace of H(t-a) is e^(-as).(1/s) But I don't see how that helps me? This isn't for homework by the way its for an exam I have in a few days time. I generally learn best from seeing looking at the...

hrm thanks for helping but still unclear. How am I allowed to substitute "t-a" = 1 ? isn't that just assigning it an arbitrary value? shouldn't I only be substituting it for another variable, if anything? Even once I get the Laplace of H(t-a), how do I then use that transform to find t.f(t) ?

Homework Statement Find the Laplace Transform of t.H(t-a) where H is the heavyside (unit step) function. Homework Equations Properties of Laplace Transforms L{t.f(t)} = -Y'(s) L{f(t-a).H(t-a)} = e-as.F(s) Maybe another one I don't know about? The Attempt at a Solution...

arghh hate that. cheers guy, appreciated.

I suspected that but I then I got upset because I didn't know where the -ve went?

Problem attached as image. Solution included. I am fine with getting the integrating factor, that bits the easy bit obviously. But Basically my specific problem is when I try to integrate sin(x).cos(x).(e^cos(x)) I understand that I need to use substitution here, but I'm not sure how they...

How did you get rid of the e^(-3s) ? thanks for helping.

Ok, so I have uploaded/attached the question and the solution. I just need help understanding the solution please. I understand how to calculate the initial inverse transform, but I included it as the reference to the second part of the question regarding the y'' + 4y' = H(t-3) Can someone...

Sir, you are of a fine callibre. Thank you greatly, seriously.