Question

If a1, a2, a3, …. upto a26 are in A.P. with common difference d , then a1, a4, a7, a10

1) must be in A.P. with common difference 5d

2) must be in A.P. with common difference 3d

3) must be in A.P. with common difference d

4) will not be in A.P.​

Answer 1

$\huge\bigstar\huge\tt\underline\blue{Answer}\bigstar$

Must be in AP with common difference 3d

(b) is Correct