A ball is thrown, and the height (in meters) as a function of time (in seconds) is h = -5t2 + 20t + 2.

How long was the ball in the air?

(4 seconds)

Step-by-step explanation:

Basically:

All you have to do is find the distance between the 2 roots of the parabola

By plugging in the value of a=-5, b=20, and c=2 into the quadratic formula:  

      Quadratic Formula = x=( -b±√(b^2-4*a*c))/(2*a)

We get 2 roots :

a) (10-√110)/5

b) (10+√110)/5

And then we add the 2 roots, thus getting 4

ANSWER: 4 seconds

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step-by-step explanation:

answer 1 : option "c"

answer 2 : option "d"

answer 3 : option "b"

answer 4 : option "d"

answer 5 : option "b"

answer 6 : option "a"

answer 7 : option "c"

answer 8 : option "d"

answer 9 : option "c"

answer 10 : option "d"

answer 11 : option "c"

answer 12 option "b"

answer 13 option "c"

answer 14 option "c"

answer 15 option "d"

answer 16 option "a"

answer 17 option "b"

answer 18 option "c"

answer 19 option "a"

answer 20 option "a"

answer 21 option "c"

d