Question

If the common differences of an $A.P.$ is $-6$. Find $a_{16}$ -$a_{12}$.

Answer 1

Given that,

$a_{16}-a_{12}=a+15d-\left(a+11d\right)$

$=a+15\left(-6\right)-\left(a+11\left(-6\right)\right)$

$=a-90-\left(a-66\right)$

$=a-90-a+66$

$=-24$