Question

A student is attempting to find a formula for the sequence below. Which statement best applies to the sample mathematical work?

Answer 1

The sample is a geometri sequencethe ratio = -9 / 3 = -3= 27 / -9 = -3so it is clearly a geometric sequencethen the formula of a geometric sequence:
an = ar^(n-1)where an is the n terma is the initial termr is the rationn is the number of term
an = 3(-3)^(n-1)is the answer

Answer 2

Answer:

Answer : B

Step-by-step explanation:

Our sequence is 3,-9,27,........This is a geometric sequence. whose first terms is 3 which is generally denoted by "a" .The common ratio is find out by taking the ration of second term to the first term. In this case it would be ,

$r=\frac{-9}{3}$

Hence r=-3  

Now the formula for the nth term of any geometric sequence is given as

$a_{n}$ = $ar^{n-1}$

Hence we now replace the value of  a and r  in this to find the right answer which is

$a_{n} = 3(-3)^{n-1}$

Hence B option is correct as the first term is not taken into the account in this answer.