Question

which term ofAP 3,8,13,18...,is 78?

Answer 1

A=3,d=8-3=5

A78=A+77D
3+5=8

8 ,Term is ap

Answer 2

a = 3

d = 5

l = 78

n = ?


We know that:-

l = a + (n-1) d

78 = 3 + (n-1) 5

78-3 = (n-1)5

75 = (n-1) 5

75/5 = n-1

15 = n-1

n = 15+1

n = 16

Therefore 78 is 16th term of AP.

Hope it helps.