Question

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Answer 1

0.64

Explanation:

0 = -16t^2 + 4t + 4

-4(4t^2 - t -1) = 0

t = [-(-1) +/- sqrt (1 - 4*4*-1)] / 8)

t = 0.64, -0.39

answer is 0.64

Answer 2

t=0.64

Explanation:

h = -16t^2 +4t +4

We want h =0 since it is hitting the ground

0 = -16t^2 +4t +4

Using the quadratic formula

a = -16 b = 4 c=4

-b ± sqrt( b^2 -4ac)

----------------------------

2a

-4 ± sqrt( 4^2 -4(-16)4)

----------------------------

2(-16)

-4 ± sqrt( 16+ 256)

----------------------------

-32

-4 ± sqrt( 272)

----------------------------

-32

-4 ± sqrt( 16*17)

----------------------------

-32

-4 ± sqrt( 16) sqrt(17)

----------------------------

-32

-4 ± 4 sqrt(17)

----------------------------

-32

Divide by -4

1 ± sqrt(17)

----------------------------

8

To the nearest hundredth

t=-0.39

t=0.64

Since time cannot be negative

t=0.64