Question 1006930
A slingshot is used to launch a marble vertically into the air with a velocity of 90 meters per second, from a starting height of 1.5 meters. The height of the marble can be modeled by the function {{{h(t)= -4.9t^2+90t+1.5}}} where h(t) is the height in meters and t is the time in seconds after the slingshot is fired. 

a.) What is the maximum height the marble will read? Round to the nearest meter.
Max height is the vertex of the parabola.
The vertex is on the LOS (Line of Symmetry)
The LOS is t = -b/2a = -90/-9.8
Max ht = h(45/4.9)
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b.) How long will the marble stay in the air before returning tot he ground? Round to the nearest second. 
{{{h(t)= -4.9t^2+90t+1.5}}}
Solve for h(t) = 0.  Use the positive value.