[tex]\begin{gathered} \text{ an = -405(-}\frac{1}{3})^{n\text{ + 1}} \\ \text{ a}_1\text{ = -405(-}\frac{1}{3})^{1\text{ + 1}}\text{ = -405(-}\frac{1}{3})^2\text{ = -405(}\frac{1}{9})\text{ = -45} \end{gathered}[/tex]
ok
[tex]\begin{gathered} \text{ an = -405(-}\frac{1}{3})^{n\text{ + 1 - 1}} \\ \text{ an = -405(-}\frac{1}{3})^n \end{gathered}[/tex]
