sigma notation = EVIL! (1 Viewer)

[moo_moo_molly]

Evaluate:

Infinity sign
Sigma (1/5)^r-1
r=1



Ok... imagine that where it says infinity sign... it is an infinity sign... and same for the sigma...

I totally don't understand what this question is asking... It's a part of series obviously...

Help = good!

 

[SoulSearcher]

It's a geometric series going (1/5)⁰ + (1/5)¹ + (1/5)² + (1/5)³ + (1/5)⁴ + .....

Sigma is just addition, therefore you are looking for the geometric sum of the series, with a = 1, and r = 1/5

In this case, we are looking for the limiting sum of the series as the terms approach infinity.

S_infinity = a/(1-r)
= 1/(1-1/5)
= 1/(4/5)
= 5/4

 

[Riviet]

The sigma sign actually means "sum of" with the numbers below and above being your first and last numbers in the series respectively. After substituting r=1 in your example, you proceed to the next integral value which is r=2, then r=3, etc. up to r=infinity.

 

[moo_moo_molly]

I ended up eventually working it out myself! But thanks for the help anyway... Sigma notation allllways confuses me!!