Thank you, makes complete sense now
So I should have expanded the factorial on the bottom to do it, and also used the complete result for
nCk rather than (5.6)?
Yep it didn't help my seeing what was going on though
I need to see everything to understand it sometimes.
Also the book didn't ask this of me so was it a good idea for me to look into it or should I sometimes just take a formula for what it is?