Recent content by countzander

Thanks for the formatting help. I attempted a solution by differentiating with respect to ##x_n##. $$\frac{\partial f}{\partial x_n} = 2x_n + \frac{A^T e^T exp(Ax+b)}{e^T exp(Ax+b)}$$ But this isn't correct, I don't think. Shouldn't ##A^T## cancel out somewhere? Can the gradient contain a...

Homework Statement http://i.imgur.com/TlDOllQ.png Homework Equations As stated. The Attempt at a Solution [/B] I'm not sure how to slay this beast. I know the gradient is just a partial derivative and that the solution likely involves multiple partial derivatives, one for each element in the...

That's what I did. As I said in the original post, the limit is 0. But because the 0 appears in the denominator, the integral is undefined. Does anyone know where the problem is?

Homework Statement Suppose that ∫X,Y(x,y) = λ2e-λ(x+y), 0 ≤ x, 0 ≤ y Find E(X + Y) Homework Equations E(X + Y) = E(X) + E(Y) The Attempt at a Solution Since the expected vale of a sum is the sum of the expected values, I attempted to find the marginal pdfs of the joint pdf...

Yes, m most certainly does divide ax and 1. It's a modular congruence relation. Because m divides the difference it must also divide the minuend and the subtrahend. At least, that should be true. But for some reason, the gcd's being greater than 1 prevents that because the congruence...

Homework Statement If gcd(a,m) > 1, then ax \equiv 1 (mod m) is impossible. Homework Equations N/A The Attempt at a Solution There is no solution per se, only an explanation. I know that m would have to divide ax and 1. Since only 1 divides 1, the statement is impossible. But that...

Computer engineering.

Money doesn't care what you like.

The cards are worth 1, 2, and 3 respectively.

Consider the game of Three." Homework Statement You shuffle a deck of three cards: ace, 2, 3. With the ace worth 1 point, you draw cards at random without replacement until your total points are 3 or more. You win if your total points are exactly 3. What is the probability that you win...

http://i52.photobucket.com/albums/g12/countzander/Untitled-1.png

Homework Statement Consider the surface S formed by rotating the graph of y = f(x) around the x-axis between x = a and x = b. Assume that f(x) ≥ 0 for a ≤ x ≤ b. Show that the surface area of S is 2π times integral of f(x)sqrt(1 + f ' (x)^2) dx from a to b. http://i.imgur.com/qFeGP.png...

Yes. After plugging x into the expression for z, would I just set y=0 and solve for z?

dz/dx= y^2 dz/dy= 2xy Then I set each one equal to zero and solved the system. (0,0) was the solution and so the critical point. (Critical points exist where the gradient is equal to zero.) Will the intersection of the boundary be something like x=((sqrt5)-1)/2 or -((sqrt5)+1)/2?

I found the critical point of z=xy^2 - 5 at (0,0), but I do not know how to relate this to the boundary.