#1
Show nCk = (n-1)Ck + (n-1)C(k-1)

that's read n choose k


it has something to do with the defitiion of nCk = n!/(k!(n-k)!)


any ideas?
GEAR


VOX AC15 / AC4
Fender MIM Sunburst Strat
epiphone les paul custom in white
Yamaha FG730s
The Tweak-O fuzz pedal
#3
It's 11.

I might have to run through my work again to see if I made any mistakes.

Edit: Yeah, I made a few mistakes.
Last edited by C O B H C at Feb 4, 2008,
#5
lawlz I know there are some brains out there
GEAR


VOX AC15 / AC4
Fender MIM Sunburst Strat
epiphone les paul custom in white
Yamaha FG730s
The Tweak-O fuzz pedal
#7
Hows that not obvious??

nCk = (n-1)Ck + (n-1)C(k-1)

through this, we can conclude, that the inverse of (n-1)C(k-1) is C-2(nk) squared. Thus, we add C-2(nk)2 + (n-1)Ck to conclude that nk(ck)= -2(n-1)+(n+c). From here, we distribute the latter expression: (n+1)+(n+k-2)=nk(ck). So, n+k2+C=(n-1)C(k-1).

Thus, C=2, N=4, and K=6

now just substitute the numbers and, VIOLA!
Quote by Alter-Bridge
My nipples. WHAT ARE THEY FOR?!?!?!?!
Quote by nick dixon
Put your penis in a raging hot fire, that should melt the bottle off
Quote by Leonheart
4e574e57363g, despite your first post on a thread almost always being PWNT you kickass.
#9
Vikings? What Vikings? We are but poor, simple farmers. The village was burning when we got here, and the people must have slain themselves.
#10
I flunked out of math
Quote by nasstyman
i don't do drugs but i fook like a pronstar and i drink like a fish and smoke like a chimney....
#11
it isn't algebra, it's a combination problem
GEAR


VOX AC15 / AC4
Fender MIM Sunburst Strat
epiphone les paul custom in white
Yamaha FG730s
The Tweak-O fuzz pedal
#12
Um...

She's a woman?

Quote by Les_Frederiksen
PlayMadness, you give me hope for mankind.

Quote by Darksucker
PlayMadness - Jesus 2.0

Quote by genghisgandhi
Society's doing great. There's a rise of people like PlayMadness. I feel pretty good about the way things are going.
#13
^ well, aren't combination and permutation algebra..?
My Spanish Hearts
#16
Quote by mju4t
it isn't algebra, it's a combination problem

if you know so much why dont you have the answer?
exactly
Vikings? What Vikings? We are but poor, simple farmers. The village was burning when we got here, and the people must have slain themselves.
#18
Quote by mju4t
Show nCk = (n-1)Ck + (n-1)C(k-1)

that's read n choose k


it has something to do with the defitiion of nCk = n!/(k!(n-k)!)


any ideas?

I'll like to qoute my probability teacher "Do it by brute force"


let's start with

(n-1)Ck+(n-1)C(k-1)=(n-1)!/(k!(n-k)!)+(n-1)!/((k-1)!(n-k+1)!)

...
just add the fractions