varyab11
Answered

Given f(n) is a geometric sequence where f(3)=32 and f(9)=72, find f(16).

I think the answer may be 64/27, but I don't know for sure.

Answer :

opudodennis

Answer:

f(16)=162

Step-by-step explanation:

-In a geometric sequence, the quotient between any tow consecutive numbers is called the common ratio,r:

[tex]r=\frac{a_n}{a_{n-1}}[/tex]

Given that f(3)=32 and f(9)=72, we can find the common ratio as below:

[tex]r=\frac{a_n}{a_{n-1}}\\\\\therefore \frac{f(9)}{f(3)}=r^6\\\\\frac{72}{32}=r^6\\\\r^6=2.25\\\\r=2.25^{1/6}[/tex]

#We substitute and use the same formula to find the nth term:

[tex]a_n=ar^{n-1}[/tex]

let f(3) be a(the first term):

[tex]a_n=ar^{n-1}\\\\a_{16}=32(2.25^{1/6})^{16-3-1}\\\\a_{16}=32(2.25^{1/6})^{12}\\\\\\=162[/tex]

Hence, f(16)=162

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