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!
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: .
For the AP: .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]: .