Atoy rocket is launched from a 4.24.2 m high platform in such a way that its height, h (in meters), after t seconds is given by the equation h equals negative 4.9 t squared plus 28.7 t plus 4.2h=−4.9t2+28.7t+4.2. how long will it take for the rocket to hit the ground?

 The toy rocket will take 6 seconds before it reaches ground.

Explanation:

 We have Height of toy rocket,

  When it reaches ground the height of toy rocket = 0 meter.

  Substituting

   So t = 6 seconds and t = -0.143 seconds( negative time is not possible)

   So the toy rocket will take 6 seconds before it reaches ground.

ammonium chloride & tallow

a and b sometimes have a positive value