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Find an equation for the nth term of the arithmetic sequence.
-1, 2, 5, 8, ...

an = -1 + 3(n)
an = -1 + 3(n - 1)
an = -1 + 3
an = -1 + 3(n + 1)

User EZLearner
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1 Answer

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In this sequence, a₁ equals -1.

The difference between each term is +3, so the coefficient for n will be 3.

In the sequence, a₂ equals 2. The following equation will fit this sequence, and will be your answer:


a_n = -1 + 3(n - 1)

Proof:

a_1 = -1 + 3(1 - 1) = -1 + 3(0) = -1


a_2 = -1 + 3(2 - 1) = -1 + 3(1) = -1 + 3 = 2
User Robert Christopher
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