HELP PLEASE!!!!!!!!!!!!!
An athlete whose event is shot put releases the shot. When the shot is released at an angle of 20°, its path can be modeled by this formula.
Y=-0.01x^2+0.4x+5.8
in which x is the shot's horizontal distance, in feet, and y is its height, in feet.
Use the formula to determine the shot's maximum distance.

Question

HELP PLEASE!!!!!!!!!!!!!
An athlete whose event is shot put releases the shot. When the shot is released at an angle of 20°, its path can be modeled by this formula.
Y=-0.01x^2+0.4x+5.8
in which x is the shot's horizontal distance, in feet, and y is its height, in feet.
Use the formula to determine the shot's maximum distance.

anonymous · Answer

okay, think about it, if x is the horizontal distance, and you want the max distance, then what are you looking for?

anonymous · Answer

y

anonymous · Answer

wouldn't you be looking for when x, when y=0 since you want the maximum distance?

anonymous · Answer

you would use
$$X=-(0.4)\pm \sqrt{(0.4)^2-4(0.01)(5.8)}$$
 over 2(0.01)

anonymous · Answer

yes

anonymous · Answer

yeah, okay :) that's right. 
so what do you get for x?

anonymous · Answer

x=6.5 or x=33.5

anonymous · Answer

it'll be over 2(-0.01)
i got a different answer. I got x as -11.3 and 51.3

and since x can't be negative, the max distance is 51.3

anonymous · Answer

i think that is my problem. I am having trouble working out the quadratic equation

anonymous · Answer

um, i find it best to do what's under the square root sign best. and write it down on a piece of paper. 
and then do the square root of it, and write that down. basically write each step's answer down rather than trying to do it all at once in the calculator. then you don't mess up :)