Question

Which term of an ap 3,15,27,39...............wilk be 120 more than 21 st term?

Answer 1

t21=3+(21-1 )12
=3+20×12=243
according to question
243+120=363
tn =3+(n-1)12
363=3+12n-12

363=12n-9

12n=372
n=372/12
=31
Hence the 31st term of the AP will be 120 more than 21st term