Question

Find a12 in the arithmetic sequence if a1 = 20 and d = 2

Answer 1

Answer:

The value of a$_{12}$ is 42

Step-by-step explanation:

The explicit formula of the arithmetic sequence is a$_{n}$ = a + (n - 1)d, where

• a is the first term

• d is the common difference

• n is the position of the term in the sequence

∵ a$_{1}$ = 20 ⇒ first term

∴ a = 20

∵ d = 2 ⇒ common difference

∵ We need to find a$_{12}$

∴ n = 12

→ Substitute them in the formula above

∵ a$_{12}$ = 20 + (12 - 1)(2)

∴ a$_{12}$ = 20 + (11)(2)

∴ a$_{12}$ = 20 + 22

∴ a$_{12}$ = 42

∴ The value of a$_{12}$ is 42