In the given expression :
[tex]a_n=-8n[/tex]
we need to find the value of n at which, an = -24
[tex]\begin{gathered} \text{Substitute the value of a}_n=-24\text{ in teh express}ionofa_n \\ a_n=-8n \\ -24=-8n \\ or \\ -8n=-24 \\ \text{Dividing both side by (-8)} \\ \frac{-8n}{-8}=\frac{-24}{-8} \\ n=3 \end{gathered}[/tex]
Thus, at n=3, the an = -24
