Question -
Answer -
Given:
First term, a = 5;last term, l = an = 80
Common difference, d =3
We know, an =a + (n – 1) d [where a is first term or a1 and d is commondifference and n is any natural number]
an = 5+ (n – 1)3
= 5 + 3n – 3
= 3n + 2
To find total terms ofthe A.P., put an = 80 as 80 is last term of A.P.
3n + 2 = 80
3n = 80 – 2
3n = 78
n = 78/3
= 26
Hence, total 26 termsexists in the given A.P.