Question

if Sn denotes the sum of the first n termof an AP what will be the value of S2 ​

Answer 1

Answer:

ANSWER

s

n

−2s

n−1

+s

n−2

=(s

n

−s

n−1

)−(s

n−1

−s

n−2

)

=a

n

−a

n−1

[∵(s

n

−s

n−1

)=a

n

]

=[a+(n−1)d]−[a+(n−2)d]

=a+nd−d−a−nd+2d

=d