# Recent content by al2521300

1. ### Finite series within finite series

Homework Statement I need to find a closed form for what at first light would be a straightforward finite series. Calculating it explicitly to a particular degree is not difficult, but I just can't find the closed form for the general case. Homework Equations For N>m, the series is...
2. ### Find the speed of the aeroplane in km/hr

Use the http://en.wikipedia.org/wiki/Law_of_sines" [Broken]. The law of sines for a triangle is just the relation that the ratio of the sine of an angle by the length of the opposite side of the triangle is a constant for each triangle. With this law you can calculate the size of both sides of...
3. ### Infinite Sum Question

1. I want to find a close expression for the following infinite sum \sum_{n=1}^{\infty}\left(\frac{1}{\sqrt{n^2+x_1 y}}-\frac{1}{\sqrt{n^2+x_2 y}}\right) Both x_i and y are greater than 0. The Attempt at a Solution I haven't got much really. I realize each sum independently is...