How do I find the summation of 1+3+9+........+n without assuming any summation formula?

.

.

Thanks a lot in advance................

Printable View

- Oct 19th 2010, 08:17 PMArkaSummation problem......
How do I find the summation of 1+3+9+........+n without assuming any summation formula?

.

.

Thanks a lot in advance................ - Oct 19th 2010, 08:38 PMEducated
As I can see from the sequence, I see that it is a geometric sequence.

You can use the formula:

Where:

a = the first term

r = common ratio, which in this case is 3

n = nth term that it goes to - Oct 19th 2010, 11:27 PMArka
- Oct 20th 2010, 01:10 AMEducated
Oh, I thought you meant without the sigma notation .

In that case, the only way that I can think of is by just adding them up manually. - Oct 20th 2010, 01:15 AMmr fantastic
- Oct 20th 2010, 01:29 AMArka
Thanks a lot..............Mr. Fantastic....