completing the square...it NEVER gets old

That takes me back 30 years to 1981 and my Math 103 class at the community college. I understood it then, it's just gibberish to me now.

... what the hell was all of that nonsense?

>> ^bamdrew:

... what the hell was all of that nonsense?


My title is sort of misleading. If you weren't being ironic (and/or too lazy to google) the quadratic formula (not equation) is one of those nasty cornerstones of calculus that you just "need to know" or at least need to be able recognize and when to apply it. It's "(-B +- the square root of B squared -4AC) divided by 2A"

Its what you use to find X in a complicated equation that uses X squared, such as "A times X squared + B times X + C = 0"
Example:

34X^2+45X+21=0

Plug those bastards (34,45,21) into the QF as respectively (A,B,C) and you'll find out what X is.

This video basically shows you why that works.

EDIT: more correctly , you'll find 2 X's one for the positive and one for the negative solution, representing the 2 points where the line f(x) crosses the X line

Thanks. I remember the quadratic equation, but unfortunately was only confused by the video... I'll watch it again sometime when not so tired.

holy crap i'm so happy i'm done with school that i don't have to deal w/ this stuff!

The quadratic equation is now considered to be the intro to intermediate algebra.