The sum of the first 3 terms of a geometric progression is 13 times its first term.Find the possible values of the common ratio of the geometric progression.
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The sum of the first 3 terms of a geometric progression is 13 times its first term.Find the possible values of the common ratio of the geometric progression.
HIQuote:
Originally Posted by mastermin346
, where a is the first term
Don worry bout the a because they will eventually cancel off.
Solve for r then .
You should also be able to cancelQuote:
Originally Posted by mathaddictHI
Don worry bout the a because they will eventually cancel off.
Solve for r then .
immediately and then use the difference of two cubes to cancel
given that
Hello, mastermin346!
Quote:
The sum of the first 3 terms of a geometric progression is 13 times its first term.
Find the possible values of the common ratio of the geometric progression.
The first three terms are: .
Their sum is 13 times the first term: .
We have: .
Therefore: .