Hi, I'm reading the preliminary algebra section of 'Mathematical Methods for Physics and Engineering' and the book explain that for a polynomial

$\displaystyle

a_nx^n+a_{n-1}x^{n-1}+...+a_1x+a_0

$

then

$\displaystyle

\sum\limits_{j = 1}^n {\sum\limits_{k>j}^n {\alpha_j\alpha_k }}=\frac{a_{n-2}}{a_n}

$

where

$\displaystyle

\alpha_n,\alpha_{n-1},...,\alpha_2,\alpha_1

$

are the zeroes of the polynomial

Please can someone explain the summation term to me, I thjnk I have an idea what it means.

Can someone write out the summation explicitly in the case of n=3

Thanks