Given: A small toy rocket is launched from a 48-foot pad. The height ( h, in feet) of the rocket t seconds after taking off is given by the formula
[tex]h=-3t^2+0t+48[/tex]
Required: To find out how long will it take the rocket to hit the ground.
Explanation: When the rocket hits the ground its height h=0. Hence
[tex]\begin{gathered} -3t^2+0t+48=0 \\ t^2=\frac{48}{3} \\ t^2=16 \end{gathered}[/tex]
which gives
[tex]t=\pm4[/tex]
Since time can't be negative. Hence t=4 seconds.
Final Answer: t=4 seconds.
