Question

In the following $AP$, find the missing terms in the boxes :
$\square ,13,\square ,3$

Answer 1

$l=a-3d13=a-dm=a+d3=a+3d$

$a-d=13$ -(i) $a+3d=3$ -(ii)

$\left(i\right)-\left(ii\right)$

$a-d-a-3d=13-3-4d=10d=\frac{-5}{2}=-2.5$

$a=13+d=13-2.5=10.5$

$l=a-3d=10.5+3\left(2.5\right)=10.5+7.5=18$

$m=a+d=10.5-2.5=8$