Question

Write the common difference of an A.P. whose $n^{th}$ terms is $3n+5.$

Answer 1

$ln=3n+5$

$l1=3\left(1\right)+5=8=a_1$

$l2=3\left(2\right)+5=11=a_2$

$a_2-a_1=d$

$11-8=d$

So $d=3$.