Question

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

Answer 1

The Geometric Sequence Formula:

$a_n=a_1r^{n-1}$

We have:

$a_1=-2,\ a_2=8,\ a_3=-32,\ a_4=128,\ ...$

$d=\dfrac{a_{n+1}}{a_n}\to d=\dfrac{8}{-2}=-4$

Substitute:

$a_n=-22\cdot(-4)^{n-1}=-22\cdot(-4)^n\cdot(-4)^{-1}=-22\cdot(-4)^n\cdot\left(-\dfrac{1}{4}\right)=5.5(-4)^n$

Answer 2

Answer:

Step-by-step explanation:

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