Factorials - Prove 1/9! + 1/10! + 1/11! = 122/11!
Question:
Prove 1/9! + 1/10! + 1/11! = 122/11!
Solution:
LHS
1/9! + 1/10! + 1/11!
= (11 x 10) / (11 x 10 x 9!) + 11 / (11 x 10!) + 1 / 11!
= (11 x 10) / (11 x 10!) + 11 / (11 x 10!) + 1 / 11!
= (11 x 10) / 11! + 11 / 11! + 1 / 11!
= 110 + 11 + 1 / 11!
= 122 / 11!
= RHS
Answer:
1/9! + 1/10! + 1/11! = 122/11! since LHS = RHS
Solution Video:
