The Student Room Group

Proof By Induction

Can someone help me here

prrof that Sum[ r(r!) ] = (n+1)! - 1

So far i have (k+1)! - 1 + (k+1)(k+1)!

pls help
Original post by B.Carmine
Can someone help me here

prrof that Sum[ r(r!) ] = (n+1)! - 1

So far i have (k+1)! - 1 + (k+1)(k+1)!

pls help


factorise the first and last terms.
Reply 2
Original post by B.Carmine
Can someone help me here

prrof that Sum[ r(r!) ] = (n+1)! - 1

So far i have (k+1)! - 1 + (k+1)(k+1)!

pls help

Try taking out a common factor of (k+1)! from (k+1)!+(k+1)(k+1)!.
factorize that mofo
Reply 4
Original post by the bear
factorize that mofo


what is a mofo?
Reply 5
Original post by notnek
Try taking out a common factor of (k+1)! from (k+1)!+(k+1)(k+1)!.


But surely i can't with that cheeky -1?
Original post by TeeEm
what is a mofo?


it is an expression with two or more factorials.
Reply 7
Original post by the bear
it is an expression with two or more factorials.


never heard of it ...
Reply 8
Ok, so, i'll do it anyway.


(k+!)![k+2 - 1/(k+1)!]

= (k+2)(k+1)! - 1

....... not right, right?
Original post by B.Carmine
Ok, so, i'll do it anyway.


(k+!)![k+2 - 1/(k+1)!]

= (k+2)(k+1)! - 1

....... not right, right?


What is (k+2)(k+1)! ?
Reply 10
Original post by 16Characters....
What is (k+2)(k+1)! ?


oh
Reply 11
i did it guys....

thank you

Quick Reply

Latest