Question 965862: Can you help me understand how to approach this sequence:
3, -6, 12, 4, 20, ?
Answer by Edwin McCravy(20054)   (Show Source):
You can put this solution on YOUR website! 3, -6, 12, 4, 20,
Look at the red numbers below. They go -9,-8,-7,-6,...
Look at the blue numbers below. They go 18,16,14,12,...
3 + -9 = -6
-6 + 18 = 12
12 + -8 = 4
4 + 16 = 20
20 + -7 = 13
13 + 14 = 27
27 + -6 = 21
21 + 12
Notice also that each blue number is -2 times the preceding red number.
Edwin
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