Determine whether each sequence is arithmetic or geometric. Sequence 1: –10, 20, –40, 80, ... Sequence 2: 15, –5, –25, –45, ... Sequence 1 is arithmetic and Sequence 2 is geometric. Both sequences are geometric. Sequence 2 is arithmetic and Sequence 1 is geometric. Both sequences are arithmetic.
Question
Answer:
1) Is geometric2) Is arithmetic
How do I know 1 is geometric? If you divide the second number by the one before it and get the same answer when going through the list of numbers it is geometric..
For example:
–10, 20, –40, 80
20 / -10 = -2
-40 / 20 = -2
80 / -40 = -2
They all have -2 when dividing them so it is geometric.
How do I know 2 is arithmetic? If you get the difference of the second number from the number that is before it and it has the same output, it is arithmetic.
For example:
15, –5, –25, –45
(-5) - 15 = = -20
(-25) - (-5) = -20
(-45) - (-25) = -20
The arithmetic rule does not work with 1 so 1 is just geometric and the geometric rule does not work with 2 so 2 is just arithmetic. Your answer would be:
Sequence 2 is arithmetic and Sequence 1 is geometric
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10 months ago
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