Recent content by pakkanen

Thank you very much jbunniii! Helped me a lot. I think we'll meet again.

Ok.. So the same operation can produce two different results?? So that l/m * k/n = (l+k)/(m2+n2) ≠ (-l+k)/((-m)2+n2) = -l/-m * k/n = l/m * k/n

Homework Statement Show that l/m * k/n = (l+k)/(m2+n2) can not be defined as an operation in Q when l,k € Z and m, n € Z\{0} I do not know what is the issue here? Should I know something about Q that this not fulfilled by the operation *?

Sorry for being unclear. I meant the subspace and not subset as you mentioned. And now it became a clear for me. Thank you very much!

Homework Statement Task: Show that U = {(x, y) | xy ≥ 0} is not a subspace of vector space R2 I wish you could help me to understand why U is not a subspace of R2x2. I have actually found a vectors u and v such that it does not belong to U (e.g. (-3,-1) +(2,2) = (-1,1) ) but is that...

Late gratitudes! I believe I get it.

This is not actually a problem but I need clarification for stochastic ordering From Wikipedia, there is stated: (http://en.wikipedia.org/wiki/Stochastic_ordering) Usual stochastic order: a real random variable A is less than a random variable B in the "usual stochastic order" if Pr(A>x)...

hmmm. of course. int(3t2-2t+81t5-9t3) that is /(t3 - t2 + 13,5t6 - 2,25t4) right? Now from 0 to 1 gives me 11,25 and the answer should be 7,5. Somewhere is still error but I can´t find it.

Ok, thank you by far. this is makes sense now but I still can´t get the right answer. I got got that the following, r = ti + 9t2j => dr = d(ti) + d(9t2j) And the F would be F = (3t2-2t)i + (9t4-t2)j Can I now take dr = (i + 9tj)dt? Ok, I have done this and int(F.dt): I had...

Ok, I have tried this but something is still going wrong. I replace the y = 3x^2 to in F(x,y,z) and I get F(x,y,z) = (2x2-2x)ux + (9x4-x2)uy So I know the y in terms of x in the vector field. I tried to somehow force r in terms of x and y and got r = 1ux and 720uy but I think this is...

First I want to greet everyone because I am new here. I have attended to applied electromagnetic course which seems to be pretty hard to understand and issues came up at very first time after I went at calculations. I try to explain this as good as possible. 1. Vectorfield F(x,y,z) =...