Question

Woo-Jin and Kiran were asked to find an explicit formula for the sequence 64\,,\,16\,,\,4\,,\,1,...64,16,4,1,...64, comma, 16, comma, 4, comma, 1, comma, point, point, point. Woo-Jin said the formula is f(n)

Answer 1

Answer:

$f(n)=64(\frac{1}{4})^{n-1}$

Step-by-step explanation:

The given sequence is

64, 16, 4, 1

$r_1=\dfrac{a_2}{a_1}=\dfrac{16}{64}=\dfrac{1}{4}$

$r_2=\dfrac{a_3}{a_2}=\dfrac{4}{16}=\dfrac{1}{4}$

$r_3=\dfrac{a_4}{a_3}=\dfrac{1}{4}$

It is a geometric series because it has a common ratio $r_1=r_2=r_3=\dfrac{1}{4}$.

First term is 64.

The explicit formula of a geometric series is

$f(n)=ar^{n-1}$

where, a is first term and r is common ratio.

Substitute a=64 and r=1/4 in the above function.

$f(n)=64(\frac{1}{4})^{n-1}$

Therefore, the required explicit formula is $f(n)=64(\frac{1}{4})^{n-1}$.

Answer 2

Answer:

Neither Woo-Jin nor Kiran

Step-by-step explanation: