Question

3, 12, 21, ...
Find the 43rd term.

Answer 1

`\sf \t_(43) = 381`381

Explanation:

Arithmetic sequence:

3,12,21 ..........

Find the common difference.

Common difference = second term - first term

d = 12 -3

`\sf \boxed{\bf d = 9}`

`\sf \boxed{\bf t_n = a + (n-1)*d}`

n = 43 ; d = 9 ; a = 3

`\sf t_(43)=3 + (43-1)*9\\\\`

= 3 + 42*9

= 3 + 378

= 381