Question

Given an=n^3-2n what is a3

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Answer 1

21

Explanation:

Try using this notation: a(n) and not an.

an=n^3-2n becomes a(n) = n^3 - 2n.

Then a(1) = 1^3 - 2(1) = 1 - 2 = -1

a(2) = 2^3 - 2(2) = 8 - 4 = 4

a(3) = 3^3 - 2(3) = 27 - 6 = 21