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Associate

Join Date: Dec 2005
Posts: 39

# Has Anyone EVER Used the Quadratic Formula?

07/03/2006 8:20 AM

How many times have you ACTUALLY USED the quadratic formula in a real-world scenerio? My son asked me why he needed to learn some abstract bit of information. "In order to pass the class," I answered pragmatically. "Did you ever do that?", he responded. So, I used the learning-the-quadratic-formula analogy... Has anybody EVER used it??? My guess is NO.

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The Engineer

Join Date: Feb 2005
Location: Albany, New York
Posts: 5060
#1

### A General Misconception

07/03/2006 9:55 AM

Actually, the quadratic equation is used in everyday life all the time, by computers. The reason we don't have to use the equation is because computers do it for us and just spit out the results.

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Join Date: May 2006
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#2

### Re:A General Misconception

07/03/2006 2:53 PM

Yea, I've used it may times, but then, I'm from the "old school" of the 60's...

Computer answers do not give the insight that a bit of "grinding" does!

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Guru

Join Date: May 2006
Location: Reading, Berkshire, UK. Going under cover.
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#3

### Re:A General Misconception

07/03/2006 4:08 PM

I'm with Jorrie - quadratics come up all over the place in basic engineering. You can't always rely on a computer program interpreting the input or the results the way you want them. If you know what the equations are, and how to solve them, you're in with a better chance.

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#12

### Re:A General Misconception

07/05/2006 4:06 PM

so, in other words "No, you have never ACTUALLY sat down with a paper and pencil and done the -b plus or minus the square root of b squared -4ac all over 2a.

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The Engineer

Join Date: Feb 2005
Location: Albany, New York
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#14

### Re:A General Misconception

07/05/2006 4:27 PM

Actually I use it all the time, but I work in Physics. One example would be vibrations in a crystal lattice. I can model the lattice as an infinite array of springs and masses, then you solve for the eigenvalues and eigenvectors. In fact, any problem where you have to solve for eigenvalues will usually involve the quadratic equation. This comes up often in Physics and Engineering.

When I said computers do it most of the time, I was referring to computers that help Pilots, Armed Forces Personel, and GPS units, Phone Repair People, Cable Repair People, Electricians etc. People in real world jobs.

Participant

Join Date: Mar 2006
Posts: 3
#9

### Re:A General Misconception

07/04/2006 3:56 PM

Some good example in engineering are combining nomal (90 degrees between0) vectors into a resultant. This could be forces, stresses, or even the real (active) and imaginary (reactive) parts of the voltage, current or power in an AC circuit. Carpenters, masons, welders, and other builders also use the equation all the time. By measuring the legs of a right triangle and calculating the length of the hypotenuse, the legs of the triangle (usually sides of a rectangular frame) can be moved until the correct hypotenuse length is achieved, indicating that the frame is square. The most common version of this uses special triangles such as the 3-4-5 (side lengths), 1-1-1.414 or sqrt(2). That way the builder doesn't have to figure square roots in their head on-site. Little building tools like this are how even ancient civilizations were able to aling huge objects without modern surveying tools.

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Join Date: Dec 2005
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#11

### Re:A General Misconception

07/05/2006 4:03 PM

So, in other words "No, you have never ACTUALLY sat down with a paper and pencil and done the -b plus or minus the square root of b squared -4ac all over 2a.

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Member

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#4

### very often...

07/04/2006 2:48 AM

well, i'm in the final year of ECSE, yeah i do use it very often to solve problems that are of course related to real world, not just punching in numbers. i guess it will be very troublesome if it werent there.. and yeah computers make our lives very easier, if u use Matlab (or even a scientific calculator these days) my guesses are u wouldnt wanna go solve it manually.. but whats underneat is still a quadratic function somone has programed. :)

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Join Date: May 2006
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#5

### Has Anyone EVER Used the Quadratic Formula?

07/04/2006 4:37 AM

Many of us used or use Quadratic Formulas, expecially those following the of old fashioned "analytic" approach, e.g. : + the lobes of an engine camshaft have a polyarmonic profiles that are partialy ruled by Quadratic Formulas; + the cilyndric rolls of a bearing, as well as the pathways of a ball bearing have quadratic profiles; + generally mechanical sliding contacts; + the pressure loss on an hydraulic or in an air duct. . . Galileo Galilei wrote: "Nature is speacking by mathematics" . Before computer simulations, formulas were the simulating tool, used to preview the behaviour of physical bodies. For some fields it can be that the most complex the model, the closest the description. The boy has to understand that there are even more complex formulas !

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Anonymous Poster
#6

### Re:Has Anyone EVER Used the Quadratic Formula?

07/04/2006 6:24 AM

I'm of the 'old school' educated in the 60's and then at university and quadratic equations are everyday occurances in my work as a designer....
But they are nothing compared to other regular maths such as complex numbers and vector analysis!!

"make something as simple as possible, but no simpler" - A Einstein.

Guru

Join Date: Jun 2006
Location: Rochester, NY
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#7

### Re:Has Anyone EVER Used the Quadratic Formula?

07/04/2006 8:18 AM

Well, I'm from the '70s school era when we started with slide rules and graduated with a TI SR-50. But we had to write the equations on the paper to show that we knew what we were doing. By the end of engineering school the HP41C or TI59 could be programmed with the equations from the homework, which was pretty much guaranteed to give 90% in MOST profs classes, although a few (you out there Dr. Heintz?) had caught on and made the problems tough enough combinations of equations that the programs wouldn't work... So yeah, we all use the quadratic equation all the time, and partial differentials, which I still struggle with. It is easier to rely on the FEA software, but if you design to that blindly you're going to end up with failures. I've noticed that my daughter's sophomore HS classes are geared more toward understanding how to use a TI89 or higher rather than writing the equations. She's kind of amazed when I just start working through the solution on paper. Kids these days! Sorry, no pithy quote.

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Eric
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#13

### Re:Has Anyone EVER Used the Quadratic Formula?

07/05/2006 4:15 PM

hey, I,m with you. My high school chemistry teacher (Mr. Marta, God bless you wherever you are) had a GIANT slide rule about 6' x 18" that hung above the black board that we had to go to the front of the class,(to the cheers and jeers of our peers) and use the appropriate scales to work out the problem we drew from "the beaker". I still ask myself when crunching numbers what the "Ball-park' answer should be... Alas, they just don't make teachers like that any more... Lake County HS, class of '80

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Active Contributor

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#8

07/04/2006 12:17 PM

Yes, I have used the quadratic formula a few times. As a matter of fact, it is the only way I have ever been able to solve a quadratic equation since I left school. I have never seen a "real life" quadratic with nice coefficients that would enable it to be factored in the "usual" way. So the quadratic formula is a versatile and powerful tool. In practice, however, if I have a computer, I use the "solver" or "goal seek" functions in a program like Excel, because often, the expression is not even quadratic. But if I had never understood high school algebra, I wouldn't even know how to go about this, using a spreadsheet.

Power-User

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#10

07/05/2006 10:05 AM

I am an late 70's early 80's (college years) civil engineer. By my graduate years of engineering I was using a progammable calculator that I programmed myself. I have two specific re-occurring uses for the quadratic equation. These are vertical curves for roadways (finding the axis of symetry locates the low or high point) and determining a water surface profile using the standard step method. However, nowadays computer software does most of my number crunching. And I use it regularly because the printout is quite orderly compared to my chicken-scratch penmanship.

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#15

07/07/2006 8:03 AM

I have actually sat down with a pencil and paper and used the quadratic formula several times in my career, and often did not use a calculator to solve the square root of (b^2 - 4ac). By the way, there are many more challenging mathematical problems than solving for roots of an equation which people run into on a daily basis.

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Anonymous Poster
#16

### Re: Has Anyone EVER Used the Quadratic Formula?

09/23/2008 7:57 AM

The brain becomes extremelly powerful and the abilities of it amazing in certain sections, honing them gives a great wealth of "useful" knowledge exchangable through different sections, ask which section it goes into, Is It aware which section is used for varying job types, eg, Cloneing verse Structural steel engineer. your young, fill up the right bits properly.

eg bored lining a workmate up against a foreign object, remembering people on a flat plain the world left behind, Biology anatomy and physiology and space science, must love kinematics.

Anonymous Poster
#17

### Re: Has Anyone EVER Used the Quadratic Formula?

03/23/2009 2:52 AM

The conept of the quadratic equation can be related to taxation. Here is a link: http://plus.maths.org/issue29/features/quadratic/index.html that deals with the historical development of the quadratic equation in antiquity. "only three things to be for sure; Taxes, Death, and Trouble."

Anonymous Poster
#18

### Re: Has Anyone EVER Used the Quadratic Formula?

04/26/2010 5:01 AM

yes When I went to the moon, It was a headache I tell ya.