The exponential function f(x) = 3(5)x grows by a factor of 25 between x = 1 and x = 3. What factor does it grow by between x = 5 and x = 7?
A) 5
B) 25
C) 125
D) 625

If a city that currently has a population of 1000 triples in size every 8 years, what will the population be in 24 years? Is the population growth modeled by a linear function or an exponential function?
A) 12,000; linear
B) 18,000; exponential
C) 20,000; linear
D) 27,000; exponential


What is the effect on the graph of the function f(x) = 2x when f(x) is replaced with f(x- 3/5)?
A) translate vertically 3/5 units up
B) translate vertically 3/5 units down
C) translate horizontally 3/5 units left
D) translate horizontally 3/5 units right

Respuesta :

                     Question # 1

Answer:

25 is the factor which grows by between x = 5 and x = 7.

Step-by-step explanation:

Considering the exponential function

[tex]f\left(x\right)\:=\:3\left(5\right)^x[/tex]

The growth factor between [tex]x=1[/tex] and [tex]x=3[/tex] is given by:

[tex]\left[3\left(5\right)^3\right]\div \left[3\left(5\right)^1\right][/tex]

[tex]\mathrm{Calculate\:within\:parentheses}\:\left[3\left(5\right)^3\right]\::\quad 375[/tex]

[tex]\mathrm{Calculate\:within\:parentheses}\:\left[3\left(5\right)^1\right]\::\quad 15[/tex]

So,

= [tex]375\div \:15[/tex]

= [tex]25[/tex]  

Similarly, growth factor between [tex]x=5[/tex] and [tex]x=7[/tex] is given by:

[tex]\left[3\left(5\right)^7\right]\div \left[3\left(5\right)^5\right][/tex]

= [tex]\frac{3\cdot \:5^7}{3\cdot \:5^5}[/tex]

[tex]\mathrm{Divide\:the\:numbers:}\:\frac{3}{3}=1[/tex]

= [tex]\frac{5^7}{5^5}[/tex]

[tex]\mathrm{Apply\:exponent\:rule}:\quad \frac{x^a}{x^b}=x^{a-b}[/tex]

[tex]\frac{5^7}{5^5}=5^{7-5}[/tex]

= [tex]5^{7-5}[/tex]

= [tex]5^2[/tex]

= [tex]25[/tex]

Therefore, 25 is the factor which grows by between x = 5 and x = 7.

                        Question # 2

Answer:

The population be in 24 years will be 27000.

Also, the population growth modeled by an exponential function as [tex]y=A\cdot \left(b\right)^t[/tex] is an exponential function.

The graph for [tex]y=A\cdot \left(b\right)^t[/tex] is also shown in attached figure.

Step-by-step explanation:

  • If a city that currently has a population of 1000 triples in size every 8 years.
  • what will the population be in 24 years?
  • Is the population growth modeled by a linear function or an exponential function?

As the city that currently has a population of 1000 triples in size every 8 years.

So, for this case

[tex]y=A\cdot \left(b\right)^t[/tex]

where

[tex]A[/tex] = Initial population amount

[tex]b[/tex] = growth rate

[tex]t[/tex] = time

Substituting the values in the function

[tex]y=A\cdot \left(b\right)^t[/tex]

[tex]y=1000\cdot \:\:3^{\frac{1}{8}t}[/tex]

So, the population be in 24 years

[tex]y=1000\cdot \:\:3^{\frac{1}{8}24}[/tex]

As

[tex]3^{\frac{1}{8}\cdot \:24}=3^3[/tex]

So

[tex]\:y=3^3\cdot 1000[/tex]

[tex]y=1000\cdot \:\:27[/tex]

[tex]y=27000[/tex]

Therefore, the population be in 24 years will be 27000.

Also, the population growth modeled by an exponential function as [tex]y=A\cdot \left(b\right)^t[/tex] is an exponential function.

                      Question # 3

Answer:

the graph of the function will translate horizontally 3/5 units right.

Step-by-step explanation:

We have to find the effect on the graph of the function [tex]f(x)=2x[/tex] when it is replaced by f(x- 3/5).

We already have an idea that rule for horizontal translation:

  • Given a function [tex]f(x)[/tex], and a constant c > 0, the function [tex]g(x) = f(x - a)[/tex] represents a horizontal shift c units to the right from f(x). The function [tex]h(x) = f(x + a)[/tex] represents a horizontal shift c units to the left.

As 3/5 > 0, so the graph of the function will translate horizontally 3/5 units right.

Therefore, the graph of the function will translate horizontally 3/5 units right.

Keywords: exponential function, translation function, growth factor

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