# Proof using binomial theorem

• Nov 17th 2012, 10:12 AM
zzizi
Proof using binomial theorem
Hi

Please take a look at the following problem:

http://i50.tinypic.com/2w5lkpd.jpg

Could someone help me out with a hint on how to prove this? I have worked out that this equation would equal 1, when x=1 and y=-2, but I could use some help on how to prove it.

• Nov 17th 2012, 10:20 AM
Plato
Re: Proof using binomial theorem
Quote:

Originally Posted by zzizi

If $n$ is even then
$1=(1-2)^n=\sum\limits_{k = 0}^n {\left( { - 2} \right)^k }\binom{n}{k}$
• Nov 17th 2012, 10:33 AM
zzizi
Re: Proof using binomial theorem
You made it too easy (Blush)

Thank you for your help Plato!
• Nov 17th 2012, 10:58 AM
HallsofIvy
Re: Proof using binomial theorem
Yeah, Plato has a way of doing that!