Worked example: Solving equations by completing the square | High School Math | Khan Academy

Sal solves x²-2x-8=0 by rewriting the equation as (x-1)²-9=0 (which is done by completing the square!).

High School Math on Khan Academy: Did you realize that the word "algebra" comes from Arabic (just like "algorithm" and "al jazeera" and "Aladdin")? And what is so great about algebra anyway? This tutorial doesn't explore algebra so much as it introduces the history and ideas that underpin it.

For free. For everyone. Forever. #YouCanLearnAnything

[CharlesG.]

who is watching this cuz you need to finish home school in quarantine

[reblogo]

Thanks Sal! This really helped me wrap my head around this :)

[MsDanijelac]

Is khan academy going to make some videos on Kirchhoff's law and some ideas behind that ? I know you are busy just asking.Because when Sal explains something it kinda gets hammered in my brain :D

[bananablu]

How would you solve this by factoring?

[aspiringcloudexpert]

3:58 Correction: what he meant to say was x minus one, not x minus negative one.