Answer :
The function is given as,
[tex]v\text{ = }\sqrt{20l}[/tex]( a ) length of the car skid marks = 180 feet.
The speed of the car is calculated as,
[tex]\begin{gathered} v\text{ = }\sqrt{20l} \\ v\text{ = }\sqrt{20\times180} \\ v\text{ = }\sqrt{3600} \\ v\text{ = 60 feet/second} \end{gathered}[/tex]Thus the car is traveling at the speed of 60 feet/sec when the skid marks are 180 feet.
(b) length of the car skid marks = 125 feet.
The speed of the car is calculated as,
[tex]\begin{gathered} v\text{ = }\sqrt{20l} \\ v=\sqrt{20\times125} \\ v=\sqrt{2500} \\ v\text{ = 50 feet/second} \end{gathered}[/tex]Thus the car is traveling at the speed of 50 feet per second when the skid marks are 125 feet.
( c ) The inverse function is calculated as,
[tex]\begin{gathered} v\text{ =}\sqrt{20l} \\ v^2\text{ = 20l} \\ l\text{ = }\frac{v^2}{20} \end{gathered}[/tex]The inverse function gives the value of the length of skid marks when the car has traveled at the speed of v feet per second.