Question

3+k,18-k,5k+1 are in A.P find k

Answer 1

Let ,

3+k = a1

18-k = a2

5k+1 = a3

d = a2 - a1 = a3 - a2

=> (18-k) - (3+k) = (5k+1) - (18-k)

=> 18-k - 3-k = 5k+1 - 18 + k

=> 15 - 2k = 6k - 17

=> -2k - 6k = -17 - 15

=> -8k = -32

=> k = -32 / -8

=> k = 4