# Homework Help: Showing a system is invariant

1. Mar 4, 2012

### rg2004

1. The problem statement, all variables and given/known data
Show that I = log(u)-u+2log(v)-v is an invariant of the following system
$\dot{u}=u(v-2)$

$\dot{v}=v(1-u)$

2. Relevant equations

3. The attempt at a solution
The question was given on a homework assignment, but I have very little idea what it is asking for and even less of an idea of how to solve it.

2. Mar 4, 2012

### tiny-tim

hi rg2004!
it just means that I-dot is zero