contestada

1) The height, h, in feet of a ball above the ground is given by h = -16t2 + 64t+ 80, where t is the time in seconds. How long does it take the ball to hit the ground? es A) 3 seconds B) 4 seconds 95 seconds D) 6 seconds​

Respuesta :

RahmaAbdullatif

Answer:

C) 5 seconds

Step-by-step explanation:

[tex]h = - 16t {}^{2} + 64t + 80[/tex]

When the ball hits the ground, the height is 0.

[tex]0 = - 16t {}^{2} + 64t + 80[/tex]

Factor out the greatest common factor: 16

[tex]0 = - 16(t {}^{2} - 4t - 5)[/tex]

Find numbers whose sum is -5 and product is - 4.

Those numbers are - 5 and 1: - 5 × 1 = - 5, - 5 + 1 = - 4

[tex]0 = - 16(t - 5)(t + 1)[/tex]

[tex]t - 5 = 0[/tex]

Or

[tex]t + 1 = 0[/tex]

So,

[tex]t = 5[/tex]

Or

[tex]t = - 1[/tex]

Since time cannot be a negative value the correct answer is 5 seconds.