In a geometric sequence, a2=108 and as 256. Write the explicit formula for this sequence.
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Answer:
The first choice is correct.
Step-by-step explanation:
First work out the common ratio r:-
a2 = a1r and a5 = a1 r^4
So r^3 = a1r^4 / a1r = 256/ 108
r = cube root (256/-108) = 4/3
So the explicit formula is 108(4/3)^(n-1)