Find the formula for the nth term of the arithmetic sequence 21, 24, 27, 30, . . . .

Question

a_n = 

Answer 1

a_n = a₁ + (n - 1)d

What is the value of n?

What is the value of d?

Can you substitute and answer?

Answer 2

Arithmetic progression :

a_n = a₁ + ( n - 1 ) d

a_{n = 21 + ( n - 1 ) 3}

a_n = 21 + 3n - 3

a_n = 19 + 3n

a_n = 3n + 19