Question

Which term of a AP 5 , 13 , 21 ,... is 181?

Answer 1

Here,a(n) = a + (n-1)d
Here, a = 5, d = 12-5 = 8, a(n) = 181
Substitute this values in to the expression,

181 = 5 + (n-1)8
181-5 = 8n-8
176+8 = 8n
n = 184/8
n = 23

So, it is 23th term of that Arithmetic Progression.

Hope this helps!