Question

The table below shows the fourth roots of different numbers:

Number (x) 16 16 81 81
Fourth root of the number (y) 2 −2 3 −3


Part A: Does the table represent y as a function of x? Justify your answer. (5 points)

Part B: The total cost f(x), in dollars, for renting a truck for x hours is shown below:

f(x) = 25x + 16

What is the value of f(20) and what does f(20) represent? (5 points)

Answer 1

20 represents how many hours you can rent a truck for $516.

Explanation:

Part A:

The table does not represent y as a function of x. In order for it to be a function, there has to be one input to be an output. For example, 16 has 2 output and 81 has 2 output. Therefore, it does not represent y as a function.

Part B:

f(x)=25x+16

f(20)=25(20)+16

f(20)=500+16

f(x)=516

20 represents how many hours you can rent a truck for $516.