Question

sum of first nterms of a.p is s¹,s²,s³.first term is 5 and c.d is 2,4,6 respectively. prove that s¹+s³=2sr​

Answer 1

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

Step-by-step explanation:

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