The formula r=2sqrt(...)5L can be used to approximate the speed r, in miles per hour, of a car that has left skid marks of length L, in feet. How far will a car skid at 70mph?

now this is getting weird. Another person assuming that sqrt(...) is the exact notation?

Go ask the person who gave you this, to show you the solution we already posted.

41.9

To find out how far a car will skid at 70mph, we can use the given formula r = 2√(5L), where r represents the speed of the car in miles per hour, and L represents the length of the skid marks in feet.

Substituting the given speed r as 70mph into the formula, we can solve for L.

We have:
r = 2√(5L)

Substituting r = 70mph:
70 = 2√(5L)

Divide both sides of the equation by 2:
35 = √(5L)

Now, square both sides of the equation to eliminate the square root:
(35)^2 = (√(5L))^2
1225 = 5L

Divide both sides by 5 to isolate L:
L = 1225/5
L = 245 feet

Therefore, a car traveling at 70mph will skid approximately 245 feet.