Recent content by Coto

How many solutions do you have when you have 0 \leq y,z \leq 10, and -10 \leq x \leq 0? I would iterate your process fixing one, then 2, then 3 variables to be negative. You could then setup an equation that adds each of those solution sets together and subtract duplicate solutions.

All values of x,y,z are within [-10,10], in order for that equation to be satisfied. How many different ways can you add 3 integers (x,y,z s.t. 0 \leq x,y,z \leq 10) to be equal to 10. Don't worry about negatives for now.

Agree with Daniiel, you can also consider it from the physical standpoint, that generally t represents time and for modelling purposes we typically restrict t \geq 0 to correspond with this notion.

This comment reminded me of the Downing effect: http://en.wikipedia.org/wiki/Downing_effect#IQ I also want to add that these two possibilities aren't the only ones, so this argument is flawed. For example, those lacking confidence in their intelligence may find a beneficial improvement to...

I would agree.

Why would you have to withdraw? If it's because the work load is too great, my suggestion is to make that choice now and save yourself the hassle later in the term. Two weeks into the course should give you an idea as to whether you can handle all of the courses, and if it turns out that there...

Hi q123, From McGill's website: http://www.mcgill.ca/applying/standards/cegep/ You need to check under the sciences category (sounds like you need an R-score of at least 27). As for Laval, I have no idea.

Something along similar lines to this problem is the Euler's disk (). What causes a sudden stop in the rotational movement of the disk? This is still an unsolved problem, though a few papers have tried to tackle it.

Hi vicsmithvic, deRham is right, don't let the requirements of a degree confine what you take. The field you're looking to get into is quite well established and there may be professors in the math department that can advise you on courses that would be useful to take. An applied math...

:) This is slightly more difficult. To solve an inverse Laplace transform requires some time and the ability to solve integrals in the complex plane (e.g. residue theory). However, you don't need to solve that integral explicitly. Rather, you want to use the properties of the Laplace...

No matter how you end up doing the question, you do end up integrating :), it's just that the integration in this question is so trivial that it can be "swept under the rug" without anyone noticing they're doing it. In this case, you've done it by considering the physical implications of your...

First off, what type of coordinate system are you using? Cylindrical? Cartesian? This is among the first decisions you must make when solving an integral of this type. It sounds like you are choosing a cylindrical coordinate system, in which case your coordinates are of the form (r,\theta,z)...

Close, you've used your boundary condition to solve for A(s) before writing the full solution of the ODE (i.e. you applied it only to the homogenous part of your solution, when you need to apply it to the full solution). In particular, \tau(x,s) = \tau_H + \tau_N = A(s)e^{-x\sqrt{\frac{s}{K}}}...

Hey dctp, Your equation, \frac{dy}{dt} = 5 \frac{dx}{dt}, tells you the rate of weight being added to the truck, denoted by \frac{dy}{dt}, as a function of the speed at which the tar paper is being added, \frac{dx}{dt}. Since you want to know how much weight is in the truck as a function of...

(Yes, I did forget the k). You've found the particular solution to the ODE, but you still need to write down the complimentary solution. That is, your solution should be of the form \tau(x,s) = \tau_C + \tau_P, where \tau_C is the solution of the homogeneous ODE, and \tau_P is the solution...