Replace r in the equation with 55 mph and solve for d.
D = 0.045(55)^r + 1.1(55)
Simplify:
D = 0.045(3025) + 60.5
D = 136.125 + 60.5
D = 196.625
At the speed limit of 55 mph the skid mark would be 196.625 feet long.
Because the skid mark was greater than that it was going faster than 55 mph.
To find the speed the car was going replace d with 250 and solve for r:
250 = 0.045r^2 + 1.1r
Multiply both sides by 1000 to remove decimals:
250000 + 45r^2 + 1100r
Subtract 250000 from both sides
45r^2 + 1100 -250000 = 0
Use the quadratic formula to solve:
R = -1100 + sqrt(1100^2 14x45(-250000) /(2 x45)
R = 63.308 miles per hour
The speed of the car was 63.3 miles per hour
Answer:
see explanation
Step-by-step explanation:
Consider
x² = 64 ( take the square root of both sides )
x = 8 , x = - 8 ← are the critical points
Then for x² > 64
x < - 8 or x > 8
