I need help on these problems regarding acceleration:

1. The head of a rattlesnake can accelerate at 50.0 m/s^2 in striking victim. If a car would have the same acceleration, how long would it take for it to reach a speed of 100.0 km/h from rest? ( First we need to figure out how many m/s 100 km/h is equal
to.)

2. A soccer player, running at 3.2 m/s, decides to accelerate. For the next 6.0 s, he speeds up with an acceleration of 0.50 m/s^2. What is his speed at the end of the run?

3. a. A windmill-style softball pitcher executes a pitch in 0.65 seconds. The ball accelerates from 0 m/s to 40 m/s. What is the acceleration?

b. Convert 40 m/s to mi/h. What is the acceleration in the above problems in mi/h/s?

And I also need help with this problem relating to quadratic equations and their discriminant:

1. For any quadratic equation ax^2+ bx+ c= 0, the sum of the solutions equal to -b/a, and the product of the solutions is equal to c/a. Show that this is true for x^2 - x - 6 = 0.