It is seemingly easy...

Algebra Level 3

Let S be the sum of the series upto 8 terms. S = 5 + 19 + 65 + 211.......(8terms).

Then S can be represented in form of 100y

S=100y

Then find "y".

Note: 100y = 100 * y

1 solution

Kartik Sharma
Nov 15, 2014

Well, I cheated(I have to admit). It is pretty hard to guess it. (Source: Oeis)

${T}_{n} = {3}^{n+1} - {2}^{n+1}$

As a result

$S = 5 + 19 + 65 + 211 + 665 + 2059 + 6305 + 19171$

$S = 28500$

Therefore, $y = 285$

I got the pattern of the sequence without cheating.. :P hehehe..

Mark Vincent Mamigo - 6 years, 7 months ago

Wow! Nice! I believe that even this man - @Krishna Ar got it without cheating!

Kartik Sharma - 6 years, 6 months ago

Of course I used OEIS too -_-

Krishna Ar - 6 years, 6 months ago

@Krishna Ar – I don't trust you nowadays! -_-

Kartik Sharma - 6 years, 6 months ago

@Krishna Ar – Hehe! I got it without cheating. I must check oeis now! ;)

Pranjal Jain - 6 years, 6 months ago

hey hey guyss! cheating is nt allowed..! It'll only help you!

Rahul Chandani - 6 years, 6 months ago