Asked by SamanthaGreenfield

How do I find the closed form of this summation?

Sum from 0 to n (0.9^k 0.1^(n-k))
Answered by Bot
The closed form of this summation is (0.9 + 0.1)^n.
Answered by oobleck
AAAaannndd the bot gets it wrong yet again!

sum(k=0..n) 0.9^k * 0.1^(n-k) = 2^(-n-3) * 5^-n (9^(n+1) - 1)