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quadratic equation

Definition/Summary
A second order polynomial equation in one variable, its general form is Click to see the LaTeX code for this image where x is the variable and a, b, and c are constants, and Click to see the LaTeX code for this image

Equations
Click to see the LaTeX code for this image

Scientists

Recent forum threads on quadratic equation
 
Breakdown
Mathematics
> Algebra
>> Equations

See Also
Mathworld
complete the square

Images

Extended explanation
Since a quadratic equation is a second degree polynomial equation, then the fundamental theorem of algebra states that two complex roots exist, counting multiplicity.

There are various analytical methods used for finding the roots of quadratic equations, one of the most common methods is the so-called quadratic formula and is derived by completing the square on the general expression shown above. The quadratic formula may be written thus,

Click to see the LaTeX code for this image

The term under the square root is known as the discriminant and can be used to determine the form of the roots of the quadratic equation.

If Click to see the LaTeX code for this image then there are two distinct real roots. Furthermore if the discriminant is a perfect square, then the two roots are also rational.

If Click to see the LaTeX code for this image then there is one repeated real root.

If Click to see the LaTeX code for this image then there are two distinct non-real roots. These two roots are the complex conjugate of each other.

Commentary

obing @ 11:49 AM Nov14-09
@ tiny-tim SREEDHARACHARYA'S RULE is about finding the root of the equation like
x = -b ± √(b"-4ac) / 2a and solving for x

obing @ 11:38 AM Nov14-09
graphical influence of physical quantity involving 2 degree variables would be of much help. it would help understanding 2 dimension more clearly

mhaze @ 11:41 PM Sep12-09
I prefer you to explain in polynomials form. arigatou

coolmadhwa @ 10:45 AM Feb27-09
it would have been better if u would have explained quadratic equations using graphs

matqkks @ 04:11 PM Nov20-08
The reason for the name discriminate for b^2-4ac is that it disciminates between real and complex roots.

olgranpappy @ 10:01 PM Oct29-08
... and I don't find any mention of that particular name here:

http://en.wikipedia.org/wiki/Quadratic_equation#History

olgranpappy @ 09:57 PM Oct29-08
"SREEDHARACHARYA'S RULE" (a.k.a. "Sridharacharya's formula") is known in the west as "the quadratic formula".

I'm sure the quadratic formula has many other names in many other places too...

Caren vUwB @ 06:51 AM Aug19-08
I only know 3 methods to find roots of quadratic equation
1. Factorization
2. Formula
3. Completing Square
I most hated completing square because it always make me confused.

tiny-tim @ 07:03 AM Jul22-08
What is SREEDHARACHARYA'S RULE? I googled and wiki'd it, but couldn't find it.

Greg Bernhardt @ 10:13 AM Jun20-08
testing latex Click to see the LaTeX code for this image


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