Question

The $4^{th}$ and ${10}^{th}$ terms of an AP are $13$ and $25$ respectively. Find the first term and the common difference of the AP. Also, find its ${17}^{th}$ term.

Answer 1

$4th$ term, $10th$ term are $13$ and $25$$a+3d=13a+9d=25(a+9d)-(a+3d)=25-136d=12d=2a=7$

First term $=7$, common difference $=2$

$17th$ term$=a+16d=39$