Math Help


Decide whether the function is an exponential growth or exponential decay function, and find the constant percentage rate of growth or decay. (5 points)


f(x) = 4.7 ⋅ 1.09x


A) Exponential decay function; 109%


B) Exponential growth function; 0.09%


C) Exponential growth function; 109%


D) Exponential growth function; 9%

Respuesta :

the tale-tell fellow is the base of the exponent ˣ.

if that number is less than 1, is a decay factor, if it's more than 1, is growth.

1.09 is cleary more than 1, so is growth, at what rate?


[tex]\bf \qquad \textit{Amount for Exponential Growth} \\\\ A=P(1 + r)^t\qquad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{initial amount}\dotfill &P\\ r=rate\to r\%\to \frac{r}{100}\dotfill &0.0r\\ t=\textit{elapsed time}\dotfill &t\\ \end{cases} \\\\\\ f(x)=4.7(1.09)^x\implies f(x)=4.7(1+\stackrel{\stackrel{r}{\downarrow }}{0.09})^x \\\\\\ r=0.09\implies \stackrel{\textit{converting it to percentage}}{r=0.09\cdot 100}\implies r=\stackrel{\%}{9}[/tex]

Exponential functions are mostly used to represent growth of population.

The true option is: (d)  Exponential growth function; 9%

The function is given as:

[tex]\mathbf{f(x) = 4.7 \cdot 1.09^x}[/tex]

An exponential function is represented as:

[tex]\mathbf{f(x) = a \cdot b^x}[/tex]

By comparison:

[tex]\mathbf{b = 1.09}[/tex]

When b is greater than 1, then the function is a growth function.

Next, we calculate the constant percentage rate of growth (r)

If b is greater than 1, then:

[tex]\mathbf{b = 1 + r}[/tex]

Substitute 1.09 for b

[tex]\mathbf{1 + r = 1.09}[/tex]

Subtract 1 from both sides

[tex]\mathbf{r = 0.09}[/tex]

Express as percentage

[tex]\mathbf{r = 0.09 \times 100\%}[/tex]

[tex]\mathbf{r = 9\%}[/tex]

Hence, the growth rate is 9%

Hence, the true option is: (d)  Exponential growth function; 9%

Read more about exponential growth and decay functions at:

https://brainly.com/question/14355665