First 3 terms of a GP are 2nd, 10th and 26th terms of an AP respectively. Show that common ratio of GP is 2.

How the heck do you do that? Thanks for helping! :)

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- Nov 1st 2008, 06:47 PMzeromeyzlAPGP Combined
First 3 terms of a GP are 2nd, 10th and 26th terms of an AP respectively. Show that common ratio of GP is 2.

How the heck do you do that? Thanks for helping! :) - Nov 1st 2008, 07:18 PMmr fantastic
- Nov 1st 2008, 07:32 PMSoroban
Hello, zeromeyzl!

You're expected to know the basics for an AP and GP.

The term of an AP is: .

The term of a GP is: .

Quote:

The first 3 terms of a GP are 2nd, 10th and 26th terms of an AP respectively.

Show that common ratio of GP is 2.

Since these are in GP: .

Equate [1] and [2]: .

. .

Since , we can divide by

Substitute into [1]: .

- Nov 1st 2008, 07:35 PMmr fantastic