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It is the question of A.P.

Let Sn denote the sum of n terms of an A.P. whose first term is a. If the common difference d is given by-----
d=Sn-KSn-1+Sn-2, then K=?
(a)1 (b)2 (c)3 (d)none of these

Please give me answer with explanation



For d, let us take n=3
d= a+2d - K(a+d) + a
d= a+2d -Ka-Kd+a
-2d+d - 2a = -k(a+d)
-d-2a = -k(a+d)
-2a-d = -k(a+d)
2a+d = k(a+d)
2a+d / a+d = k
2 S₁ / S₁ = k
∴K = 2
option (b) is correct

Thank You......!!!!!!!!!
Mark as brainliest if helpful...
Yours, Jahnavi.
2 5 2
thanks jahnavi
i will mark it as brainlist one
but i have a doubt why we suppose that n=3
No u can take any but it is n=3 is a simple calculation to find the answer
I'm sis n thanks
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