Problem

$1<\quad$ Use differences to find a pattern in the sequence. $2,6,14,31,62,112,186$ Assuming that the pattern continues, the eighth term should bej

Solution

Step 1 :Given the sequence \(2, 6, 14, 31, 62, 112, 186\)

Step 2 :Calculate the differences between consecutive terms to get \(4, 8, 17, 31, 50, 74\)

Step 3 :Calculate the second differences to get \(4, 9, 14, 19, 24\)

Step 4 :Notice that the second differences are increasing by 5 each time, suggesting a cubic sequence

Step 5 :Predict the next second difference to be \(29\) by adding 5 to the last second difference

Step 6 :Calculate the next difference by adding the predicted second difference \(29\) to the last difference \(74\) to get \(103\)

Step 7 :Calculate the next term by adding the next difference \(103\) to the last term \(186\) to get \(289\)

Step 8 :\(\boxed{289}\) is the eighth term in the sequence

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Source: https://solvelyapp.com/problems/31293/

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