Answer:
possible values of 4th term is 80 & - 80
Step-by-step explanation:
The general term of a geometric series is given by
Where a(n) is the nth term, r is the common ratio (a term divided by the term before it) and n is the number of term
- Given, 5th term is 40, we can write:
- Given, 7th term is 10, we can write:
We can solve for a in the first equation as:
<em>Now we can plug this into a of the 2nd equation:</em>
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<em>Let's solve for a:</em>
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Now, using the general formula of a term, we know that 4th term is:
4th term = ar^3
<u>Plugging in a = 640 and r = 1/2 and -1/2 respectively, we get 2 possible values of 4th term as:</u>
possible values of 4th term is 80 & - 80