Please help:

A fastball is hit straight up over home plate. The balls height, "h" (in feet), from the ground is modeled by" h(t)=-16t^2+80t+5 where t is measured in seconds.

A) What would be the vertex of this function
B) What is the practical meaning of the vertex
C) Where is the ball after 1 second
D) When is the ball 101 feet above the ground
E) What is the horizontal intercept?

Question

Please help:

A fastball is hit straight up over home plate. The balls height, "h" (in feet), from the ground is modeled by" h(t)=-16t^2+80t+5 where t is measured in seconds.

A) What would be the vertex of this function
B) What is the practical meaning of the vertex
C) Where is the ball after 1 second
D) When is the ball 101 feet above the ground
E) What is the horizontal intercept?

ipwnbunnies · Answer

To find the x-value of the vertex of the parabola (which would be the time, t)
use this:
$$\frac{-b}{2a}$$
Oops, where ax^2 + bx + c = 0 is the general form of a quadratic equation

anonymous · Answer

okay :)

ipwnbunnies · Answer

Then you plug that x-value into the equation again, that'll give you the y value, which is the maximum height of the baseball.

anonymous · Answer

-16t^2+80t+5=0

ipwnbunnies · Answer

o.o Yes, that's the equation. b = 80 and a = -16

anonymous · Answer

t=14(10±√105) 
t≈5.06173769149,−0.06173769149

anonymous · Answer

thats the first part i think lol

ipwnbunnies · Answer

Idk what you just did. o.o

anonymous · Answer

lmao.

ipwnbunnies · Answer

-b/2a finds the x-value for the vertex. We're not using quadratic formula.

anonymous · Answer

-2.5?