Question

which term of A.P:3, 15, 27, 39,............. will be 120 more than its 21st term​

Answer 1

Pls mark brainliest

Step-by-step explanation:

A. P 3,15,27

A21=3+20*12

=243

3+(n-1)12=243+120

(n-1)12=363-3

n-1=360/12

n-1=30

n=31

Answer 2

21st term= a+20d=3+240=243

120more=243+120=363

363 is some nth term

It can be written as 3+(n-1)d

363=3+(n-1)12

n=31

Therefore and is 31st term