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Sequences: Write a formula for a geometric sequence

Write an explicit or recursive formula for the nth term of a geometric sequence, given the value of several of its terms. Based on HS common core standard F-BF.A.2 and TEKS 12D.

Which expression is used to determine the nth term of the geometric sequence 6, 12, 24, 48, …?

6(2)^(n-1) 2(6)^(n-1) 6(2)^n 2(6)^n
Which expression represents the nth term of the geometric sequence 2, 8, 32, 128, …?

4(2)^(n-1) 2(4)^n 4(2)^n 2(4)^(n-1)
What is the explicit formula for the geometric sequence 100, 10, 1, 0.1…, if a1 = 100?

an = 100(0.1)^n an = 100(0.1)^(n-1) an = 0.1(100)^n an = 0.1(100)^(n-1)
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