I need some serious help with quadratic eqations. HELP ASAP

toasty

New member
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Mar 2, 2006
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6
Ok here's the problem I'm working on. h is heigt in meters and t is time inseconds. h=-4.9t(sqaured)+2.07t. I kinda missed the days we went over this in class so if someone could show me how to find maxium hieght, time to reach maximu hieght, and time from initial bounce to other side. (the problem is about ping pong) i really need a response asap
 
ADDITON

sorry i know it says no problems from your textbook exactly and whatnot but I'm really in trouble here...if i could get some help I would be very happy.
 
The max of an upside down parabola is given by the vertex of the parabola.

max height = \(\displaystyle \frac{-b}{2a}\)

Daon
 
ok

yeah i got that. now how do i find the time it takes to get there
 
come on

ive had this up 4 quite awhile and i got one no helpful respose. Come on. everyother post has gotten a repsonse that helped them except mine. geez.
 
Re: come on

toasty said:
ive had this up 4 quite awhile and i got one no helpful respose.
Your post has been up for barely one hour, and the reply you received was helpful.

Please keep in mind that there is no paid staff waiting on-hand to provide you with instant solutions. You need to show your work, and then expect to wait hours, if not days, for a volunteer to surf by and provide assistance.

Thank you for your consideration.

Eliz.
 
Re: come on

toasty said:
ive had this up 4 quite awhile and i got one no helpful respose. Come on. everyother post has gotten a repsonse that helped them except mine. geez.
Try to be patient. Most of the people here who help know a lot, but not everyone knows how to do everything, or maybe they spent so much time on another post, they decided to take a break. I've been there.

The height of the second equation is found the same way. the constant added on the end has no affect, it is still \(\displaystyle \frac{-b}{2a}\). When you take calculus or physics in the future you will learn why.

The time that it takes to get there can be found by using the quadratic equation (or by factoring if possible).

For example, if you are given: h = -2t^2 +4t - 1, the maximum height is:

\(\displaystyle \frac{-4}{2*(-2)} = \frac{-4}{-4} = 1\)

The time that it takes to get to its maximum height of 1 can be found by putting 1 in for h:


\(\displaystyle 1=-2t^2+4t-1\)

\(\displaystyle 2t^2-4t+2=0\)

You can factor this, or use the quadratic equation. Since it is factorable,

\(\displaystyle (2t-2)(t-1) = 0\).

From here we get t=1.
Get the idea?
 
sorry i was a little impaitent but i have a big test tomorrow and im completly lost here. i still need a little clarification on the steps you took. thanks.
 
Which part don't you understand?
-----------------
Gene

PS. You get better response by posting new questions as a new post. Only the person who answered the first is likely to see the new one unless someone else is just running through those which have been answered.
 
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