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In a quadratic

Name: Anonymous 2007-07-01 22:05 ID:OiZHtUlb

The discriminant is equal to the first derivative.

Does that have any special meaning (geometrically or otherwise), or is it just an algebraic coincidence?

Name: 4tran 2007-07-01 22:27 ID:JRUBkP0j

That's not even true...

The first derivative is a function from C->C
The discriminant is a number in C

Name: Anonymous 2007-07-02 8:44 ID:uYNyxYVp

Don't discriminate against numbers >_<

Name: Anonymous 2007-07-02 11:34 ID:owvDG3dp

You should ask this guy I know; he's an expert programmer cause he's read SICP.

Name: Anonymous 2007-07-03 17:09 ID:rUQcepFA

AX^2 + BX + C = 0

(+/-)sqrt(B^2 - 4AC) = 2AX + B

manipulates into the quadratic formula

The reason I was asking is because I read it in some vedic math books. Most of the stuff in there becomes common sense after a bit of thinking, but this just seems like it's out there.

Name: Anonymous 2007-07-03 18:49 ID:mdDjn8Mq

(+/-)sqrt(B^2 - 4AC) = 2AX + B

in the above, X is the value which makes the quadratic function zero, whereas in the first derivative, x is a function of y.

also, the discriminant is the expression under the root sign,
d=b^2-4ac

Name: Anonymous 2007-07-03 18:51 ID:mdDjn8Mq

>>6
oops y is a function of x, in other words, x can vary.

Name: 4tran 2007-07-04 1:33 ID:nvRkiG81

mmm, I see what you're saying.  It's probably better phrased as "the discriminant is equal to the derivative at the roots".

What I do know: if the discriminant is 0, then there exists a real, double root.  This also requires the derivative to be 0 at the root.  In this case, they are equal.  This should generalize to higher order polynomials.

What I'm speculating: when the discriminant is not 0, this is probably just an algebraic coincidence.

Name: Ikerous 2007-07-04 3:53 ID:QU8jHCKW

the quadratic formula is -b/2a (+/-) sqrt(b^2 - 4ac)/ 2a = x

-b/2a is the vertex of the parabola.  The sqrt(b^2 - 4ac) is the distance on each side (Hence +/-) from the vertex to the zero's.

The vertex of a parabola exists when the first derivative is zero.   2ax + b = 0 when X = -b/2a.  Hence the relationship.

Name: Anonymous 2007-07-04 3:56 ID:QU8jHCKW

Should say sqrt(b^2 - 4ac)/2a not sqrt(b^2 - 4ac)

Name: Anonymous 2007-07-06 20:37 ID:h6hDktDk

>>9

Thank you, I see it was all a matter of breaking it down into it's special events and seeing the correlations at those points.

Name: Anonymous 2009-03-18 3:18

Don't call me gay, but I need some mary jay!

Marijuana MUST be legalized.

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