Xcel energy uses the equation c (x) =7.1+23logx to determine the cost of electricity for x hours. A. What would the function c^-1(x) allow you to calculate. B. Find c^-1(x). C. If a customer can afford $15 per month for electricity, how long can he or she have electricity turned on?

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Answer:

Step-by-step explanation:

Note that the cost function is [tex]c(x) = 7.1+23\ln(x) [/tex], which gives us the cost of electricity for x hours of consumption

a). The function [tex]c^{-1}(x)[tex] which is the inverse function, tells us given a cost, the amount of hours we can consume electricty.

b) Consider the equation

[tex]y=7.1+23\ln(x)[/tex]

To find out the inverse function, we interchange the labels of x and y and solve for y, that is

[tex] x = 7.1+23\ln(y)[/tex]

when solved for y we have

[tex] e^{\frac{x-7.1}{23}}= y [/tex]

So the inverse function is given by [tex]c^{-1}(x) = e^{\frac{x-7.1}{23}}[/tex].

c) We will use the inverse function to find the amount of hours the customer can use eelectricity. It is simple obtained by evaluating the inverse function at the desired cost (i.e [tex]c^{-1}(15)[/tex])

that is

[tex]e^{\frac{15-7.1}{23}} = 1.409[/tex]

that is, the custome can consume at most 1.41 hours of electricity.

Answer:

Please read the answer below

Step-by-step explanation:

We have the function

[tex]y(x)=7.1+23logx[/tex]

A. With c^{-1}(x) we can calculate the hours of electricity for a definite cost

B.

c^{-1} can be calculated by taking into account that:

[tex]c^{-1}(x)=\frac{1}{c(x)}=\frac{1}{7.1+23logx}[/tex]

the denominator must be different of zero, hence we have for x:

[tex]7.1+23logx=0\\\\7.1+logx^{23}=0\\\\logx^{23}=-7.1\\\\10^{logx^{23}}=10^{-7.1}\\\\x^23=10^{-7.1}\\\\x=10^{\frac{-7.1}{23}}=0.49\approx0.5[/tex]

x must be different of 0.48

C.

By taking apart the function c(x) we have:

[tex]logx^{23}=15-7.1=7.9\\\\10^{logx^{23}}=10^{7.9}\\\\x=10^{\frac{7.9}{23}}=2.2h[/tex]

x=2.2h

hope this helps!