Question

Write the geometric sequence in function notation.

7, 14, 28, 56, 112, ...
3
Ax) = (7). ()x-1
f(x) = (7) · (2)X-1
O AX) = (7) . (3)X-1
Rx) = (2) (+)*-1

Answer 1

f(x) = (7) ∙ (2)x–1

Explanation:

The first term in the sequence is 7, and the common ratio is 2. Using the explicit formula and writing it in function notation results in f(x) = (7) ∙ (2)x–1.

Answer 2

a(n) = 7*2^(n - 1)

Explanation:

The first term of the given geometric sequence, 7, 14, 28, 56, 112, ... , is 7, and the common ratio is 2. Each new term is twice the previous term.

Thus the general formula for the geometric sequence becomes

a(n) = 7*2^(n - 1).

As a check, let's see whether this formula correctly predicts the fourth term (56): Here n = 4, and so a(4) = 7*2^(4 - 1) = 7*2^3 = 7*8 = 56. Yes.