These questions are pertaining to College Algebra

Question

1 a) A baseball is hit so that its height, s, in feet after t seconds is

                                        s = -16t^2 + 44t + 4

 

For what time period is the ball at least 32ft above the ground?

 

b) For what time period is the ball greater than 28ft above the ground?

Answer 1

32 ≤ -16t² + 44t + 4

-16t² + 44t - 28≥ 0

4t² - 11t + 7 ≤ 0

(4t - 7)(t - 1) ≤ 0

 

4t - 7 = 0

4t = 7

t ≤ 7/4

 

t - 1 = 0

t = 1

 

So, the ball reaches 32 feet at 1 second and comes back down to 32 feet at 1 3/4 seconds.

 

1 ≤ t ≤ 1 3/4