# Homework Help: Extended binomial theorem

1. Mar 18, 2010

### talolard

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

Calculate $$\sqrt{1/20}$$ using the extended binomial theormem. (a precision of k=4 is enough)

3. The attempt at a solution

$$\sqrt{1/20}= (1 + (-19/20) )^{1/2}= \sum( choose (1/2,k)*(-19/20)^k) = 1- 1/2*19/20-1/8*361/400+1/16*6589/8000 = 0.72...$$ is wrong.
1. The problem statement, all variables and given/known data

Where is my mistake?
Thanks
Tal
2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Mar 18, 2010

### vela

Staff Emeritus
You made a simple sign mistake somewhere, it seems.