From the table below, determine whether the data shows an exponential function. Explain why or why not.

(x) -5, -4, -3, -2
(y) 0.5, 2, 8, 32

A) Yes; the domain values are at regular intervals and the range values have a common factor 8.
B) Yes; the domain values are at regular intervals and the range values have a common factor 4.
C) No; the domain values are not at regular intervals.
D)
No; the domain values are at regular intervals and the range values have a common factor 4.

Please help, and please give me an explanation on the answer you choose because I need to make corrections. Please.

Respuesta :

B) Notice how you can get the next value multiplying by 4 each time, while x changes by one:

0.5*5=2, 2*4=8, 8*4=32

This function is 4^(x+4)*2 = 512*4^x, 512*4^(-5)=512/1024=0.5, it works!

Answer:

Option B-  Yes; the domain values are at regular intervals and the range values have a common factor 4.

Step-by-step explanation:

Given : The data

(x) -5,   -4,  -3,   -2

(y) 0.5,  2,   8,   32

To find : The data shows an exponential function or not

Solution :

The general form of an exponential form is [tex]y=ab^x[/tex]

To check whether the data give the exponential function we form equation with the help of two points and verify the other two points .

[tex]y=ab^x[/tex]

Let x= -5 and y=0.5

[tex]0.5=ab^{-5}[/tex]

[tex]\frac{0.5}{b^{-5}}=a[/tex] ......[1]

Let x= -4 and y=2

[tex]2=ab^{-4}[/tex]

[tex]\frac{2}{b^{-4}}=a[/tex] .........[2]

Equate LHS because RHS is equal in equation [1] and [2]

[tex]\frac{2}{b^{-4}}=\frac{0.5}{b^{-5}}[/tex]

[tex]\frac{b^{-4}}{b^{-5}}=\frac{2}{0.5}[/tex]

[tex]b=4[/tex]

Put back in [2]

[tex]\frac{2}{4^{-4}}=a[/tex] .

[tex]a=2\times4^4[/tex]

[tex]a=2\times256=512[/tex]

a=512 and b=4

Exponential function - [tex]y=4(512)^x[/tex]

To verify this function put

1) x=-3

[tex]y=512(4)^{-3}[/tex]

[tex]y=\farc{512}{64}[/tex]

[tex]y=8[/tex]

The point satisfied.

2) x=-2

[tex]y=512(4)^{-2}[/tex]

[tex]y=\farc{512}{16}[/tex]

[tex]y=32[/tex]

The point satisfied.

Therefore, The given data is an exponential function [tex]y=4(512)^x[/tex]

The domain values are at regular intervals and the range values have a common factor 4 because b=4 and the change happen but value of b remain same.

Hence, Option B is correct.

Yes; the domain values are at regular intervals and the range values have a common factor 4.