# Homework Help: If for n-dimensions f>=0 , prove the integral of f >=0

1. Mar 8, 2015

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
a) The furthest I have got to understanding the solution is that I need to find a way to show that sup(f(x1,x2,...,xn) >= 0. Intuitively and graphically I can see why the statement is obvious, I'm just having a hard time starting to write the proof...

2. Mar 8, 2015

### Dick

If $f(x_1,..x_n) \ge 0$ then it's pretty obvious $sup(f(x_1,..x_n)) \ge 0$. If you don't have a convenient theorem like if $f \ge g$ then $\int f \ge \int g$, then you might have to use the definition of the integral.