Question

What is the common ratio for the following geometric sequence?

-5, -10, -20, -40

Answer 1

Answer:

Divide each term by the previous term to determine whether a common ratio exists. 21=242=284=2168=2 2 1 = 2 4 2 = 2 8 4 = 2 16 8 = 2 The sequence is geometric because there is a common ratio.

Answer 2

a(1)=‐5 , a(2)=‐10 , a(3)=‐20 , a(4)=‐40.

The common ratio of a geometric sequence is the ratio of any term to its preceding term.

So, we get,

$\frac{a(2)}{a(1)} = \frac{ - 10}{ - 5} = 2$

$\frac{a(3)}{a(2)} = \frac{ - 20}{ - 10} = 2$

$\frac{a(4)}{a(3)} = \frac{ - 40}{ - 20} = 2$

Hence, The required answer is 2.

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