Recent content by tatiana_eggs

Homework Statement Calculate the gravitational potential due to a thin rod of length l and mass M at a distance R from the center of the rod and in a direction perp. to the rod. Homework Equations integral form of Gauss's law wrt gravitation The Attempt at a Solution Can I use...

Ah of course, 0 to 2 will be my x bounds. Thank you for the time you took to make the diagram. I see my mistake before. I redrew it with help from your picture and it is clear that my lower bound is x=0.

Thank you for the reply, Jack, in my drawing I see that my bound for x would start at x=2. I want to say my lower bound is x=-2 because of where z=-x crosses x=2-y^2. Is that right?

Homework Statement Hi guys, I need help setting up an integral. Problem: Compute the integral f(x,y,z)=xyz over the solid region bounded below by plane z=-x, above by z=x, and otherwise b the parabolic cylinder x=2-y^2 This is not a surface integral, is it? Because the problems...

Probably not one book, but you can follow the standard curriculum set in a uni: First would be a calculus book, like Stewart's. Second maybe Boas' Mathematical Methods in the Physical Sciences. I think the second edition you can get super cheap. Anything you don't understand in Boas you can...

That was just the hint I needed, Halls. Thanks! Finally got it.

Homework Statement Find the real and imaginary part of sin(4+3i) Homework Equations sinx = \frac{e^z - e^(-z)}{2i} cosx = \frac{e^z + e^(-z)}{2} sin(iy) = i\frac{e^y - e^(-y)}{2} cos(iy) = \frac{e^y + e^(-y)}{2} various trig identities The Attempt at a Solution So I used sin(x+y) trig...

Homework Statement Use special comparison test to find if \frac{2+(-1)^n}{n^2+7} is convergent or divergent.Homework Equations Special comparison test using the convergent series \frac{1}{n^2} and taking the limit as n-> infinity of my initial series \frac{2+(-1)^n}{n^2+7} divided by my...

I would try first replacing sin (2x) with 2 sin x cos x then do u sub and let u = cos x. Try that and see if it helps

Oh and I finally figured out the substitution thing. I realized I didn't need to sub 3u into the numerator

Thanks Statdad, Dickfore and Hurkyl, so very much!

Oh wow, I just did it in degree mode and it produced the answer consistent with the back of the book.

Hurkyl, it was in radian mode.

so I got du = (e^x)/3 dx. What do I do with this expression? I thought I was supposed to solve for dx, and plug that into my integral with my u's. Is that not right? integral: 3u / (9u^2 + 9) * 3 / (e^x) du

The derivative of u. I thought I had to take the derivative of my subsitution and solve for dx to sub that back into my integral.