Question 159246
To find the max height, you need to find the vertex. Notice how the equation {{{h=-5t^2+20t+1.2}}} (I just rearranged the terms) is in the form {{{y=at^2+bt+c}}}. So you can use the formula {{{t=(-b)/(2a)}}} to find the value of "t" at the vertex (ie the time it takes to get to the peak). Once you find "t", plug it into {{{h=-5t^2+20t+1.2}}} to find the height



-----------------------------------



To find the time it takes for the object to hit the ground, simply plug in h=0 into {{{h=-5t^2+20t+1.2}}} to get {{{0=-5t^2+20t+1.2}}}. Now use the quadratic formula to solve for "t"



Hopefully this explanation made sense. If not, then just repost the problem or email me at jim_thompson5910@hotmail.com