On a coordinate plane, an exponential function approaches y = 0 in quadrant 1 and increases into quadrant 2. It goes through (2, one-ninth), (1, one-third), (0, 1), and (negative 1, 3).
Analyze the graph of the exponential decay function.

The initial value is
.



The base, or rate of change, is
.



The domain is
.

Respuesta :

Answer:

Initial value (a) = 1

Base (b) = ¹/₃

Domain = (-∞, ∞)

Step-by-step explanation:

General form of an exponential function:

  [tex]y=ab^x[/tex]

where:

  • a is the initial value (y-intercept)
  • b is the base (growth/decay factor) in decimal form
  • x is the independent variable
  • y is the dependent variable

If b > 1 then it is an increasing function.

If 0 < b < 1 then it is a decreasing function.    

Initial value (a)

The initial value is the y-intercept.

The y-intercept is where the curve crosses the y-axis (when x = 0).  

We have been given the point (0, 1), therefore the y-intercept is 1, and so:

  • Initial value (a) = 1

Base (b)

To find the value of the base (b), substitute the found value of a and one of the given points (2, ¹/₉) into the equation:

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

[tex]\implies \dfrac{1}{9}=(1)b^2[/tex]

[tex]\implies b^2=\dfrac{1}{9}[/tex]

[tex]\implies \sqrt{b^2}=\sqrt{\dfrac{1}{9}}[/tex]

[tex]\implies b=\dfrac{1}{3}[/tex]

Therefore:

  • base = ¹/₃

Finally, the equation of the given exponential function is:

[tex]y=\left(\dfrac{1}{3}\right)^x[/tex]

Domain

The domain of a function is the set of all possible input values (x-values).

The domain of the found exponential function is unrestricted.

Therefore:

  • Domain = (-∞, ∞)

Learn more about exponential functions here:

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