Recent content by aija

Ok thanks, it's clear now

You mean the integral in the attachment is wrong? It's part of an example solution not done by me so I thought it would be right but it would help a lot to know that there is an error in the example solution.

This is part of an example solution to a problem about integrating a function in a [0,1]x[0,1]x[0,1] cube. I just don't understand how the midst function is integrated like in the attached picture. This is the same integral in wolfram alpha and it gives a different solution...

Homework Statement integrate dx / (x^2 - 1)^2 Homework Equations The Attempt at a Solution There is nothing i can substitute to get rid of x. Except x=sqr(t), but then dx is 1/2sqr(t) so i get: ∫( dt / (t-1)^2 * 2sqr(t) ) and it's still impossible to integrate.

yes, i understood that as well, thanks

Oh thanks. I accidentally used diameters as areas...

Still getting a wrong answer. Is something wrong in my equation? with values A_1 = 3.5 cm A_2 = 2.5 cm v_1 = 2.0 m/s i get 2.8 m/s and it's wrong. the correct answer was 3.9 m/s. But why did I get a wrong answer?

Thank you I got it. So the volume flow rate vA is constant so v_1*A_1=v_2*A_2 V_2=-(v_1*A_1)/A_2

Homework Statement Water flows in a pipe with speed 1.5 m/s at point 1. The diameter of the pipe at point 1 is 4cm and the diameter at point 2 is 3cm. density of water: 998.2071 kg/m^3 What's the speed of the water at point 2? Homework Equations I think you need to use this. I just have no...

Thanks, I tried it again and now I get it. I just made a little mistake calculating 2-3 (not -5) It's weird because I counted this twice (did the same mistake twice) and checked that I had counted everything totally right but didn't notice this.

From wikipedia: It doesn't say that anything should be done to the elements of the matrix so I guess it would be just A B (columns of A written as rows)

Ok, but according to wolfram alpha this matrix still has 3 eigenvectors, and I'm wondering why can i only find the first two eigenvectors using the method i used?

If you know what's diagonalization, you can skip this. For a to be diagonalizable, A=PDP^-1, where P is an invertible matrix whose columns are A's eigenvector (order of these columns doesn't matter). C is a diagonal matrix that has all A's eigenvalues So for a 3x3 diagonalizable...

If A is a diagonal n x n matrix, A has non-zero elements only at indices (k,k), k belongs to {1, n} so for a 4x4 matrix it looks like this a 0 0 0 0 b 0 0 0 0 c 0 0 0 0 d Tridiagonal matrices can have non-zero elements also at indices (k, k+-1) so a 4x4 tridiagonal matrix would look like...

Matrix A= 2 1 2 1 2 -2 2 -2 -1 It's known that it has eigenvalues d1=-3, d2=d3=3Because it has 3 eigenvalues, it should have 3 linearly independent eigenvectors, right? I tried to solve it on paper and got only 1 linearly independent vector from d1=-3 and 1 from d2=d3=3. The method I used...