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3 years ago

Write the explicit formula that represents the geometric sequence -2, 8, -32, 128

1 answer:

6 0

So hmm the first term is -2

and if we divide one term by the term before it, we'd get the "common ratio" "r"

so hmm say -32/8 that gives us -4, so r = -4

thus $\bf n^{th}\textit{ term of a geometric sequence}\\\\
a_n=a_1r^{n-1}\qquad 
\begin{cases}
a_1=\textit{first term}\\
r=\textit{common ratio}\\
----------\\
a_1=-2\\
r=-4
\end{cases}\implies a_n=-2(-4)^{n-1}$

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