The length of a traffic accident tire skid mark (M) in feet is given by M=6.4√(s^2) - 3.8 (no more square root) - 7.4 where s is the speed of the vehicle in miles per hour. If a police officer measures the tire skid mark to be 150 feet, how fast was the car going?

Question

dumbcow · Answer

solve the equation
$$6.4 \sqrt{s^2 -3.8} -7.4 = 150$$
first add 7.4 to other side
next divide by 6.4
next square both sides
add 3.8 to other side
Finally take square root