Question

Given the formula for an arithmetic sequence f(9) = f(8) + 4 written using a recursive formula, write the sequence using an arithmetic explicit formula.

f(9) = f(1) + 1
f(9) = f(1) + 4
f(9) = f(1) + 8
f(9) = f(1) + 32

Answer 1

f(9) = f(1) + 32

Explanation:

Answer 2

The answer is option d

Explanation:

The given formula is for arithmetic sequence is

f(9) = f(8) + 4

By using the formula an = a +(n-1)d

Where a is the first term and d is the common difference and n is the nth

term

∵ By substituting in the main equation we get

a + 8d = a +7d +4

d = 4

So by analyzing the options we get answer as option d

f(9) = f(1) + 32

a +8d = a +32

8×d =32

8×4 = 32

32 = 32

∴The answer is option d