Question
Question: If S<sub>1</sub>, S<sub>2</sub>, S<sub>3</sub> are the sum of n. 2n, 3n terms of an A.P. then 3(S<su...
If S1, S2, S3 are the sum of n. 2n, 3n terms of an A.P. then 3(S2 –S1) =
A
S3
B
2S3
C
4S3
D
None of these
Answer
S3
Explanation
Solution
S1 = 2n [2a + (n –1) d]
S2 = 22n [2a + (2n –1) d]
S3 = 23n [2a + (3n –1) d]
S2 –S1 =2n [2a + d(3n –1)]
S2 – S1 = 3S3
3(S2 – S1) = S3