Question

A ball is thrown in the air from a ledge. Its height in feet is represented by 

f(x) = –16(x2 – 6x – 7), where x is the number of seconds since the ball has been thrown. The height of the ball is 0 feet when it hits the ground.

How many seconds does it take the ball to reach the ground?
 

A.6
 

B.7
 

C.1
 

D.16

Answer 1

check the picture below.

`image`

it cannot be -1, because is a seconds amount after moving.