Question

The braking distance y in feet that it takes a car to stop on​ wet, level pavement can be estimated by y=1/25x^2 ​, where x is the speed of the car in miles per hour. Find the speed associated with the braking distance of 196 feet.

Answer 1

in essence, find "x" when y = 196

`y = \cfrac{1}{25}x^2\qquad \stackrel{\textit{when y = 196}}{196=\cfrac{1}{25}x^2}\implies (196)(25)=x^2 \\\\\\ √((196)(25))=x\implies {\Large \begin{array}{llll} \stackrel{(m)/(h)}{70}=x \end{array}}`