SOLUTION: The height y (in feet) of a ball thrown by a child is y= −1/14x² + 4x + 5 where x is the horizontal distance in feet from the point at which the ball is thrown. (a) How high

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Question 1167951: The height y (in feet) of a ball thrown by a child is y= −1/14x² + 4x + 5 where x is the horizontal distance in feet from the point at which the ball is thrown.
(a) How high is the ball when it leaves the child's hand?
? feet
(b) What is the maximum height of the ball?
? feet
(c) How far from the child does the ball strike the ground? Round your answers to the nearest 0.01.
? feet
I need help on this one!!!

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
It is 5 feet high, the constant in the equation.
-
vertex is at x=-b/2a or -4/-1/7 or 28
when x=28 then y=-56+112+5=61 ft.
-
it strikes the ground when y=0
rewrite quadratic as -x^2+56x+70=0 or x^2-56x-70=0
x=(1/2)(56+/- sqrt (3136+280)) sqrt term=58.45
x=57.22 ft.
graph%28300%2C300%2C-10%2C60%2C-5%2C70%2C%28-1%2F14%29x%5E2%2B4x%2B5%29