**P. 3954.** Cars of length *l* travel with uniform velocity of *v* and pass a road sign. The distance between them is *x*. The greater their speed the greater the distance between them. The relationship between their speed and the distance between them is given by the function *x*=*v*^{2}, where is constant, characteristic to all cars. What is the velocity at which the most cars go past the road sign during a given time?

(4 points)

**Deadline expired on 12 March 2007.**