Question

3, -9, 27, -81,... Explicit Formula an = -9 . 3n-1 an = 3 . -3n-1an = -9 . 27n-1 an = 3 - 3 ( n- 1 )

Answer 1

To find the explicit form we have find r so we divide the second term by the first one so:

$r=-\frac{9}{3}=-3$

Now we know that the formula is:

$\begin{gathered} a_n=a_0r^{n-1} \\ a_n=3(-3)^{n-1} \end{gathered}$

So the answer is option D