Question

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

Answer 1

Answer:

AP : 3,8,13,18.......,is 78?​

a1 = 3, a2=8, a3=13, a4=18

d= a2-a1

d= 8-3

d=5

an=78

a1+ (n-1)d =78

3+(n-1)5 = 78

(n-1)5 = 78-3

n-1 = 75/5

n-1 = 15

n=15+1

n=16

therefore there are 16 terms in the AP