Answer:
- pattern: common ratio of -1/3
- next: 5
Step-by-step explanation:
When looking for patterns in a sequence, it is useful to look at differences, ratios, and differences of differences. Here, the terms have a common ratio:
405/-1215 = -135/405 = 45/-135 = -15/45 = -1/3
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For this sequence, each number is -1/3 times the previous number.
The next number is (-15)(-1/3) = 5.
