Quadratic Equation

[Zen]

I know there are some big brains here so I'm posting this for a friend.

Friend says "I need a real life example of the quadratic equation. A student wants to understand it better and wants to know why it is practical. I need something visual or kinetic. Any ideas?"

So, any ideas?

[Biciclista]

I'll ask my son the mathematician

[Flybye]

101 Uses for the quadratic equation right here. There is also a 101B. How I lived my life without knowing this information is beyond me. I am now a complete woman
http://plus.maths.org/issue29/featur...ndex-gifd.html

[Biciclista]

here is what he said:

There's no easier equation to explain: projectile motion!

Toss a ball to somebody, and it takes a parabolic path. Want to know
when it will hit the ground? Solve the quadratic equation!

[Zen]

I did do a google but my head started to explode, so thanks to the three of you

[shootingstar]

Dearie looked over my shoulder at the link: "That's trigonometry".

Now, uforgot should know, the math teacher.

But I looked at the link....the application would be what I learned in design layout for calligraphic work used by the medieval priest scribes. The formula gives the "golden mean" for the perfectly proportional rectangle within a rectangle. But we didn't use a mathematical formulae..just drawing straight lines, measuring off a border and running a line diagonally through the opposite ends of corners.

Or maybe I have poor memory. My notes are somewhere.

Perhaps Mimi's son can confirm that the golden mean is quadratic equation:
http://ezinearticles.com/?Golden-Pro...ean&id=3772732
http://www.goldenmeangauge.co.uk/

http://www.cyberspaceorbit.com/ironhart/goldensec.html

[Zen]

Oh, no.
This is a bit more involved than the golden mean. Even I could understand that.

[Tuckervill]

here is what he said:

There's no easier equation to explain: projectile motion!

Toss a ball to somebody, and it takes a parabolic path. Want to know
when it will hit the ground? Solve the quadratic equation!

That's completely impractical. Why would you want to know when it will hit the ground? Most people use intuition and space/time intelligence to determine that. And it takes all the fun out of throwing a ball if you make kids do math about it.

Okay, that's my rant, but a more practical example is that of a missile or bullet. You really need to know where your projectile is going to fall when using weapons. However, the engineers have already done the equation and the user only has to set a few buttons or crank a lever to a certain angle. If you take it from the POV of the engineer, then that's a very practical application.

Karen

[Veronica]

I've always thought quadratic equations were really about learning logical thinking.

Veronica

[Tri Girl]

I haven't heard the term: quadratic equation in YEARS!
I guess that's what I get when I teach elementary school- no higher lever math here (whew!).

[uforgot]

I read Zen's question wrong, so I'll repost. Quadratic EQUATION,not formula, right?

1. Parabolic motion, (projectile motion) is indeed the best application. Life is rarely a straight line. By the time students take Algebra, they are expected to be able to solve and graph these equations. Life is rarely a straight line. Analyzing graphs is a part of logical thinking and problem solving. No one expects little kids to do this while they play in the yard! On the other hand, my physics students solve these projectile motion problems using sin, cos and tan, and then using the acceleration due to gravity. I might add that they also hate these problems, so I include one on every test.lol

2. It's not Trig. They learn these in Algebra I in 8th grade. Three years before they step into my Trig class. The reason so many people don't know them is simply because they don't remember them. You've all probably done them.

3. An example that isn't a parabola. Say you have a garden and you want it to be 2 ft longer than it is wide. You also want it to be 24 square feet. To find the dimensions you should plant, you would take the length times the width for the area. x(x - 2) = 24. You would then set up the equation x^2 - 2x -24 = 0. Factor it: (x-6)(x + 4) = 0. x would then be either 6 or -4. Since you can't have a negative length, the length of the garden is 6 and the width (6-2) is 4.

If she needs any help, just message me. Now if she wanted to know about the quadratic FORMULA, let me know. That's how I first interpreted it.

[Zen]

Great example, I can almost understand it but this stuff makes me dizzy.
I was posting for a friend who teaches anatomy. I'm sure she'll have no problem.
Thanks.

[Flybye]

Geez, if it is anatomy you need help with then ask away

[malkin]

Passing math classes was as real life as it ever got for me.

[IFjane]

Passing math classes was as real life as it ever got for me.

Me too, malkin!