Police use the function f(x)+ Square root of 20x to estimate the speed of a car, f(x), in miles per hour, based on the length, x, in feet,of it’s skid marks.A mortorist is involved in an accident. A police officer measured the car’s skid marks to be 245 feet long. estimate the speed at which the motorist was traveling before braking. if the posted speed limit is 50 miles per hors and the motorist tells the officer he was not speeding, should the officer believe him? Solve
Answer:
Did you mean that the equation was f(x)=sqrt(20x)? The way you have written it there is no equals sign, rendering the problem unsolvable. If you did, in fact, mean f(x)=sqrt(20x), the answer is x=70. We can solve this by substituting 245 in for f(x) and simplifying. 20*245=4900 and the square root of 4900 is 70, therefore f(x)=70. So yes, the motorist was speeding.
