What is the discriminant for the polynomial ax^2+bx+c

Which is the equation of a line perpendicular to the line with the equation 3x+4y=8

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. how many hours after the truck's departure will the two meet?

Find the condition that the zeros of the polynomial f(x) = x^3+3px^2+3px+r may be in a. p.