The function [tex]F(x)=\frac{9}{5} x+32[/tex] models the temperature in degrees Fahrenheit, given the temperature, [tex]x[/tex], in degrees Celsius.

Part A

Which expression models [tex]F^{-1}[/tex]?
A. [tex]\frac{5}{9} x-32[/tex]
B. [tex]\frac{5}{9}(x+32)[/tex]
C. [tex]\frac{9}{5} x-32[/tex]
D. [tex]\frac{5}{9}(x-32)[/tex]

Part B

What is the value of [tex]F^{-1}(50)[/tex] and what does it represent?



Answer :

Sure, let's go through the problem step-by-step.

### Part A:
We are asked to find the inverse function [tex]\( F^{-1}(x) \)[/tex] of the function [tex]\( F(x) = \frac{9}{5}x + 32 \)[/tex].

To find the inverse function, we follow these steps:

1. Set [tex]\( y = F(x) \)[/tex]:
[tex]\[ y = \frac{9}{5}x + 32 \][/tex]

2. Solve for [tex]\( x \)[/tex]:
- Subtract 32 from both sides to isolate the term with [tex]\( x \)[/tex]:
[tex]\[ y - 32 = \frac{9}{5}x \][/tex]

- Multiply both sides by [tex]\( \frac{5}{9} \)[/tex] to solve for [tex]\( x \)[/tex]:
[tex]\[ x = \frac{5}{9}(y - 32) \][/tex]

3. Replace [tex]\( y \)[/tex] with [tex]\( x \)[/tex] to express the inverse function:
[tex]\[ F^{-1}(x) = \frac{5}{9}(x - 32) \][/tex]

Therefore, the correct expression that models [tex]\( F^{-1}(x) \)[/tex] is:
[tex]\[ \boxed{\frac{5}{9}(x - 32)} \][/tex]

This corresponds to option 4 from the given choices.

### Part B:
Next, we need to evaluate the inverse function at [tex]\( x = 50 \)[/tex]. That is, we need to find the value of [tex]\( F^{-1}(50) \)[/tex].

Using the inverse function we found:
[tex]\[ F^{-1}(x) = \frac{5}{9}(x - 32) \][/tex]

Substitute [tex]\( x = 50 \)[/tex]:
[tex]\[ F^{-1}(50) = \frac{5}{9}(50 - 32) \][/tex]

Perform the calculation inside the parentheses first:
[tex]\[ 50 - 32 = 18 \][/tex]

Then multiply by [tex]\( \frac{5}{9} \)[/tex]:
[tex]\[ F^{-1}(50) = \frac{5}{9} \times 18 = 10 \][/tex]

The value of [tex]\( F^{-1}(50) \)[/tex] is:
[tex]\[ \boxed{10} \][/tex]

Interpretation:
This value represents the temperature in degrees Celsius when the temperature is 50 degrees Fahrenheit. So, [tex]\( F^{-1}(50) = 10 \)[/tex] means that 50 degrees Fahrenheit is equivalent to 10 degrees Celsius.

To summarize:
Part A: The inverse function is [tex]\( \frac{5}{9}(x - 32) \)[/tex].
Part B: The value of [tex]\( F^{-1}(50) \)[/tex] is 10, meaning 50 degrees Fahrenheit is equal to 10 degrees Celsius.