Question

For what value of k will $k+9,2k-1$ and $2k+7$ are the consecutive terms of an A.P.?

Answer 1

We have $k+9,2k-1$ and $2k+7$ as consecutive terms of an A.P.

Then, $2(2k-1)=k+9+2k+7$ [if a, b and c are in A.P. then $2b=a+c$]

$4k-2=3k+16$

$k=18$