Option D: A(n) = a + (n – 1) d
Solution:
To identify the formula for finding the nth term of an arithmetic sequence.
Let a be the first term.
d be the common difference of the each term.
n be the term of the number.
A(n) be the nth term of the arithmetic sequence.
Arithmetic formula:
A(n) = a + (n – 1) d
Example: 1, 4, 7, 10, 13, 16, 19, ...
This is a arithmetic sequence.
a = 1, d = 4 – 1 = 3.
To find the 5th term:
Substitute this in the above formula, we get
A(n) = a + (n – 1) d
A(5) = 1 + (5 – 1) 3
= 1 + 4(3)
= 1 + 12
A(5) = 13
In the given sequence 5th term is 13.
Hence Option D is the correct answer.
A(n) = a + (n – 1) d
