# vertex of parabola

• October 7th 2008, 01:35 PM
cwarzecha
vertex of parabola
At a time t seconds after it is thrown up in the air, a tomato is at a height (in meters) of f(t)=−49t^2+60t+3 m.

What is the average velocity of the tomato during the first 5 seconds?
How high does the tomato go?
How long is the tomato in the air?
• October 7th 2008, 03:06 PM
skeeter
forgot a decimal in your function ...

$f(t) = -4.9t^2 + 60t + 3$

$V_{avg} = \frac{f(5) - f(0)}{5 - 0}$

t-value for the vertex of f(t) (time at the top of its trajectory) is $\frac{-b}{2a}$ ... then find $f\left(\frac{-b}{2a}\right)$

total time ... set f(t) = 0 and solve for t
• October 7th 2008, 03:19 PM
cwarzecha
How do you know what b and a are?
• October 7th 2008, 03:20 PM
cwarzecha
never mind i got it, thanks