Given two specific terms of geometric sequence. Find the common ratio and first term. Show the solution.
a(2)=4 ; a(5)=32
please can you teach me the step by step because I really can't understand T-T
The easiest method is to calculate r, or common ratio:
This becomes: , and then:
With common ratio being 2, and using the 2nd term, 4, we get:
First term or
OR
The LONGER method:
Use the equation for a term of a GP, which is: , and the 2nd term (4) to find an equation in
Repeat the process but this time, use 5th term (32) to find an equation in
You will then have a system of equations in , which you then solve to get the values of the 1st term (a1), and r, the common ratio.