# Binomial Coefficient problem

1. Jan 14, 2005

### gschjetne

I'm working on an IB mathematics portfolio, and here's a problem I don't understand:
It's not specified what $a$ and $b$ is supposed to represent. That's where I need some explanation.
I already made a nice Pascal triangle all the way to the 10th row.
All help is appreciated.

2. Jan 14, 2005

### dextercioby

My guess is that it comes from the expansion:

$$(a+b)^{n}=\sum_{k=0}^{n}C_{n}^{k} a^{n-k}b^{k}$$

Daniel.

PS.Can u handle the $(n-1)$ term part??

3. Jan 14, 2005

### gschjetne

Thanks, I'll give it a try