If the discriminant of an equation is zero, which of the following is true of the equation?​

Graph y ≥ -x^2 - 1. click on the graph until the correct graph appears.

Acar started driving from city a to city b, distance between which is 620 miles, at a rate of 60 mph. two hours later a truck left city b and started moving towards city a at a rate of 40 mph. what distance from city a is the point where the truck and the car will meet?

I'm confused on this could anyone me and show me what i need to do to solve it.