Question

Find the first term of the following geometric sequence:

, 15, 45, 135, 405, ...

Answer 1

the answer would be 5

Answer 2

the answer is 5. If you doit like this you first see what you can multiple to get to 15 first.
For example
15 and 45. What you multiply by 15 to get 45?
The answer would be 3.
So let's do do it the opposite way be dividing 15 by 3 which will give 5
So you see that everything is multiplied by 3 and the first term of the sequence is 5
hope that helps