Question

The first and last term of an AO are a and l respectively. If S is the sum of all terms of the AP and the common difference is given by l²-a²/k-(l+a), then k =

Answer 1

Answer:

We have, S=

2

n

(a+l)⇒

a+l

2S

=n ...(1)

Also, l=a+(n−1)d⇒d=

n−1

l−a

=

a+l

2S

−1

l−a

(from (1))

=

2S−(l+a)

l

2

−a

2

∴k=2S