How do you find the common ratio for $7,14,28,56,128,...$ ?

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Answer 1 · 2016-07-24T21:17:46

Ignoring the $128$ (which should probably have been $112$ ), the common ratio is $2$ .

For this sequence to have a common ratio, the ratio between any pair of consecutive terms must be the same.

So if this sequence does have a common ratio, then we can look at any pair of consecutive terms, e.g. $7, 14$ to find the ratio:

$14/7 = 2$

This ratio is the same for $28/14$ and $56/28$ , but $128 != 2*56$ .

I suspect a typo in the question. The value you would expect is $112$ rather than $128$ .

How do you find the common ratio for 7,14,28,56,128,...7,14,28,56,128,...?