The first and last term of an A.P. are a and l respectively. If S is…

Question

The first and last term of an A.P. are a and l respectively. If S is the sum of all the terms of the A.P. and the common difference is given by l^2 - a^2k - ( l + a ) then k = ?

Accepted Answer

Option B. 2S. Answer & Solution Answer: Option B Solution: & S = n/2 ( l + a ) & l = a + ( n - 1 )d & d = l^2 - a^2k - ( l + a )\, and\, also\,d = l - an - 1 & l - an - 1 = ( l + a ) ( l - a )k - ( l + a ) & 1n - 1 = l + ak - ( l + a ) & k - ( l + a ) = ( n - 1 ) ( l + a ) & k = ( n - 1 ) ( l…