# Algebra simplification - don't understand

• May 10th 2012, 10:33 AM
jooby
Algebra simplification - don't understand
Hi

I'm working on a textbook mathematical induction problem - part of which involves an algebra simplification that I don't understand.
Just wondering if anyone can explain how they get to the right hand side?

((k-1)(k-1 +1) (2(k-1)+1)) /6 = ((k-1) k(2k - 1)) /6

I don't understand how they managed to ditch so many ks and other numbers.
I don't get algebra at all so the most basic explanation would be good.

Thanks
• May 10th 2012, 02:41 PM
HallsofIvy
Re: Algebra simplification - don't understand
Quote:

Originally Posted by jooby
Hi

I'm working on a textbook mathematical induction problem - part of which involves an algebra simplification that I don't understand.
Just wondering if anyone can explain how they get to the right hand side?

((k-1)(k-1 +1) (2(k-1)+1)) /6 = ((k-1) k(2k - 1)) /6

It's largely arithmetic. For example, -1+ 1= 0 so that middle term is k-1+ 1= k. And 2(k- 1)= 2k- 2 so that 2(k-1)+1= 2k- 2+ 1= 2k- 1.

Quote:

I don't understand how they managed to ditch so many ks and other numbers.
I don't get algebra at all so the most basic explanation would be good.

Thanks