Question

4. Which term of the AP:3, 8, 13, 18,...,is 78?​

Answer 1

Explanation:

= t1 = a = 3

t2 = 8

t3 = 13

t4 = 183

d = t2 - t1

d = 8 - 3

d = 5

Formula:- tn = a + ( n - 1 ) d

78 = 3 + ( n-1) 5

78 = 3 + 5n -5

78 -5n = 3 -5

72n = 2

n = 36

36 th is 78.