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Write an explicit rule for the arithmetic sequence below.

| n | 1 | 2 | 3 | 4 | 5 |
|----|----|----|----|----|
| f(n) | 2.7 | 4.3 | 5.9 | 7.5 | 8.1 |

A. [tex]\( f(n) = 1 + 1.6(n-1) \)[/tex]

B. [tex]\( f(n) = 2.7 + 1.6(n+1) \)[/tex]

C. [tex]\( f(n) = 2.7 + 1.6n \)[/tex]

D. [tex]\( f(n) = 2.7 + 1.6(n-1) \)[/tex]


Sagot :

Let's find the explicit rule for the given arithmetic sequence following a step-by-step approach:

1. Identify the first term:
The first term [tex]\( f(1) \)[/tex] of the sequence is 2.7.

2. Determine the common difference:
To find the common difference, subtract the first term from the second term.
[tex]\[ \text{Common difference} = 4.3 - 2.7 = 1.6 \][/tex]

3. Form the explicit formula:
The general formula for an arithmetic sequence is:
[tex]\[ f(n) = \text{first term} + (n - 1) \times \text{common difference} \][/tex]

Substituting the known values:
[tex]\[ f(n) = 2.7 + (n - 1) \times 1.6 \][/tex]

Therefore, the explicit rule for the arithmetic sequence is:
[tex]\[ f(n) = 2.7 + 1.6(n - 1) \][/tex]

So, the correct answer is option [tex]\( \text{d} \)[/tex]. [tex]\( f(n) = 2.7 + 1.6(n-1) \)[/tex].