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The following table represents a function.


x y

-2 -1/8

-1 -1/2

0 -2

1 -8

2 -32


Which exponential function does this table represent?

Ay = 8(4)^(x-1)
By = -8(4)^(x-1)
Cy = 8(1/4)^(x-1)
Dy = -8(1/4)^(x-1)

Verified Answer :

bcalle

The answer is B. Plug in the x values to check the y values.

Answer:

B.

Step-by-step explanation:

To find the right exponential function, we can just take x-values an replace them into the given functions. The one that give the correct y-values will be the answer.

For \(x=-2\), let's see which function gives \(y=-\frac{1}{8}\)

\(y=8(4)^{x-1} \\y=8(4)^{-2-1}\\ y=8(4)^{-3}\\ y=\frac{8}{4^{3} }=\frac{1}{8}\)

You can observe that function A is not the correct one, because it gives a positive result. However, function B can actually be the answer, because it woud give the same y-value than A but negative, as we need. Let's see

\(y=-8(4)^{x-1}\\ y=-8(4)^{-2-1}\\ y=-8(4)^{-3}\\ y=-\frac{8}{4^{3} }=-\frac{1}{8}\)

Let's evalute for \(x=0\)

\(y=-8(4)^{0-1}=-8(4)^{-1}= -\frac{8}{4}=-2\)

Which is right.

Therefore, the right answer is B.