Answer:
2
Step-by-step explanation:
The output increases by a factor of 4 when the input increases by 2 units:
(b^(x+2))/(b^x) = 4 = b^2
√4 = b = 2
The output value increases by a factor of 2 as each input value increases by 1.
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That rate of increase could also be -2. I see nothing in the problem setup that requires the sequence not alternate signs.
