A geometric sequence is defined recursively by an = 6an -1 . The first term of the sequence is 0.75. Which of the following is the explicit formula for the nth term of the sequence?

Verified Answer :

caylus

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\(u_{1}= \frac{3}{4} \\ u_{2}= \frac{3}{4}*6^{1} \\ u_{3}= \frac{3}{4}*6^{2} \\ u_{4}= \frac{3}{4}*6^{3} \\ ...\\ \boxed{u_{n}= \dfrac{3}{4}*6^{n-1} } \\\)

Answer:

The explicit formula for the nth term of the sequence is \(a_n=0.75(6)^{n-1}\).

Step-by-step explanation:

The recursive formula of a GP is

\(a_n=6a_{n-1}\)

It is given that the first term is 0.75, it means

\(a_1=0.75\)

The next terms of GP are

\(a_2=6a_{2-1}=6\times (0.75)=4.5\)

\(a_3=6a_{3-1}=6\times (4.5)=27\)

The GP is defined as

\(0.75,4.5,27\)

Here the first term is 0.75 and the common ratio is 6.

The explicit formula for the nth term of a GP is

\(a_n=ar^{n-1}\)

The explicit formula for the nth term of the sequence

\(a_n=0.75(6)^{n-1}\)

Therefore the explicit formula for the nth term of the sequence is \(a_n=0.75(6)^{n-1}\).