Quadratic Equations: Write function for height of ball, etc.

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chrozer

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Shane Bechler is about to punt the ball. Let "t" represent the # of seconds from the moment his foot constacts the football. The height of the ball when Lechler makes contact is 4 feet. After one seconds, the ball has reached a height of 44 feet and after two seconds, the ball has reached a height of 52 feet. Hint: h(t) = -16t^2 + vt + h should not be used.

a. Write a quadratic function in standard form for the information given.
b. After how many seconds does the football reach its maximum height and what is the height?

P.S. I tried to work this problem using my TI 84 Calculator by finding the Quadratic regression but it is in the same form as the hint, but I can't use that form. So help me out...I'm really confused. How would I work this problem out?
 
I'm not sure what you mean by using the regression feature of your calculator, since you aren't doing a regression on a list of data points...?

How does your book define "standard" form? (There is, ironically, no standard definition to this term.) :shock:

Note: The equation in the "hint" is strictly for vertical motion. Presumably the punter is not trying to send the ball directly up over his head! :wink:

Eliz.
 
Well I input in to the calculator 1 and 2 in list 1 as "x" and 44 and 52 in list 2 as "y" so that's how i found the quadratic equation of y = -16x^2 +56x +4.

In the book standard equation is defined as ax+by = c, but this is a worksheet made by my teacher.
 
chrozer said:
Well I input in to the calculator 1 and 2 in list 1 as "x" and 44 and 52 in list 2 as "y" so that's how i found the quadratic equation of y = -16x^2 +56x +4.
Click to expand...
I'm not sure what you're doing with your calculator, but you cannot find a quadratic equation from only two general points, and your calculator should not be able to come up with a quadratic regression for this. (It should give you an error message.) Perhaps you also included the initial value, (0, 4)...?

chrozer said:
In the book standard equation is defined as ax+by = c, but this is a worksheet made by my teacher.
Click to expand...
This might be the standard form for a straight line, but you're working with a quadratic, so you need to find the definition for the standard form of that.

Eliz.
 
Oh yeah...i did include the point (0, 4).

And for the standard form for the equation of a quadratic line is y= ax^2 +bx + c. Srry that's what I mean't to type. Didn't know what I was thinking.
 
If you were supposed to use regression software, then it appears you have found the correct equation. I don't know what your instructor intended by the "hint", other than perhaps that the noted equation should not be your starting point. :?:

Eliz.
 
Ok thanx. I just asked my teacher this morning and she said it was right. Thanx anyways.
 
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