Question 727876
The height of the diver above the water (in feet) is
{{{h= -16(t-1.5)(t+1)}}} with {{{t}}} measured in seconds after the diver leaves the board.
The diver hits the water at the time when {{{h=0}}}
The equation {{{h= -16(t-1.5)(t+1)}}} tells you that {{{h=0}}} when {{{t-1.5=0}}} and when {{{t+1=0}}}
{{{t-1.5=0}}} --> {{{highlight(t=1.5)}}} means that the diver hits the water {{{highlight(1.5)}}} seconds after leaving the board.
 
NOTE:
{{{t+1=0}}} --> {{{t=-1}}} does not make sense, because it means 1 second before jumping.
However, an alien seeing a video showing the diver from the time the diver leaves the board may conclude that the diver was shot out of the water 1 second before the start of the video.