Question

Use the sequence below to complete each task. 3, -15, 75, ... a. Identify the common ratio (r). b. Write an equation to represent the sequence. C. Find the 5th term (as) Algebra), 2013 → B I y Default A A : = 5 川里

Answer 1

a)

This is a geometric sequence, this means that each value of the sequence is multiplied by the common ratio to determine the next number.

For the sequence {3,-15,75}

Divide one of the given numbers by the number before it on the sequence to determine the common ratio

$r=\frac{-15}{3}=-5$

The common ratio for this sequence is r=-5

b)

a is the first value of the sequence

r is the common ratio

k is the place on the sequence of the required value

You can calculate said value using

$ar^k$

c)

For

a=3

r=-5

k=5

The value fo the sequence is

$ar^k=3(-5)^5=-9375$