Question

The sum of first n terms of three Ap's are S1. S2& S3. The first term of each AP is 1 & their common differences are 2,4 &6
respectively. Prove that s1+s₂ =2s2
​

Answer 1

Answer:

Answer

S

n

=

2

n

[2a+(n−1)d]

Using the above formula, we get:

S

1

=

2

n+n

2

Similarly,

S

2

=n

2

and

S

3

=

2

3n

2

−n

S

1

+S

3

=

2

n+n

2

+

2

3n

2

−n

=

2

n+n

2

+3n

2

−n

=

2

4n

2

=2n

2

=2S

2

∴S

1

+S

3

=2S

2