Tagged Questions
5
votes
6answers
310 views
How to simplify a complicated Sum in terms of power Sums?
For example, I have:
$a=\sum _{r=1}^n x_r
\left(\left(\sum _{i=1}^n
x_i-x_r\right){}^2-\sum
_{i=1}^n x_i^2\right)$
...
10
votes
6answers
906 views
Replacing composite variables by a single variable
To replace a single variable by another variable, one can simply use the the replace all (/.) operator (e.g., ...
7
votes
6answers
765 views
How do I replace a variable in a polynomial?
How do I substitue z^2->x in the following polynomial z^4+z^2+4?
z^4+z^2+4 /. z^2->x
...
