# Homework Help: Find the average of f(x)=sqrt(1-x) on the interval [-1,1]?

1. Jun 10, 2010

### Chandasouk

Please show work. There was a negative sign that appeared in the solution and I don't know why.

I know $$\sqrt{}(1-X)$$ can be rewritten as (1-X)^1/2 and then you use the power rule to integrate but that gives you

(1-x)^3/2
------------
3/2

2(1-X)^3/2
--------------
3

My book shows

-(1-X)^3/2
------------
3/2

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

2. Relevant equations

3. The attempt at a solution

2. Jun 10, 2010

### Dick

You integrate that by using the substitution u=1-x. So dx=(-du). Then use the power rule on the u integral. That's where the '-' sign comes from.