Question

which term of an A.P 3,8,13,18,.....is 78?

Answer 1

 For the following A.P : 3,8,13,18,------, 78 
First term (t1) = a = 3,common difference (d) = 8 - 3 = 5 and last term (tn) = 78 

The general term of A.P is 
tn = a + (n - 1) d 
78 = 3 + (n - 1)5 
78 = 3 + 5n - 5 
78 = - 2 + 5n 
78 + 2 = 5n 
80 = 5n 
80/5 = n 
16 = n 
n= 16 

16th term of A.P : 3,8,13,18,is 78. 

please mark it as brainiest

Answer 2

It Is the 16th term.