Q: What is the tenth term of the sequence: 4, 12, 36, 108, …?
Explanation: It’s a geometric sequence because each term is multiplied by 3 to get the next term. The common ratio (r) is 3. You *could* just keep multiplying by 3 until you get to the tenth term. It’s not the most efficient way, but it works.
The ‘best’ way, if you know it, is to use the formula for the nth term of a geometric sequence:
Oh, and my TI-84 Plus program ‘NTHTERM’ will find this answer for you.