Problema Solution
a ball is hit upward. Its height h in feet after t seconds is h=-16t^2+80t=4. at what times is the ball 100 feet in the air?
Answer provided by our tutors
the equation is given incorrectly (note there are two equal signs): h=-16t^2+80t=4
we assume the correct expression is intended to show that the ball was hit at a height of 4 feet and should therefore be:
h=-16t^2+80t+4
we solve "h=-16t^2+80t+4" for h=100
100 = -16t^2 + 80t + 4
solving for 't' we have t = { 2, 3 }
the ball is 100 feet in the air at t=2 seconds and t=3 seconds