Number of solutions to a system of equations algebraically | High School Math | Khan Academy

Sal solves several examples where he reasons about the number of solutions of systems of equations using algebraic reasoning.

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

[yoanski]

In the second example you can just divide the first equation by (-2) and you would see that the two equations are identical and it's faster that way.

[aplanenerdandagamenerd]

When he was doing the second equation, I was thinking "Sal, You're not hiding it very well that the bottom equation is half of the top."

[akramzakriti]

that is easy for me and I'm from morocco

[akshaykumart.r.]

5:20 If they both have same slope shouldn't they have infinitely many solutions or no solutions??

[MdAshraf]

I used demos for the first equation and in demos I saw they are parallel lines.

[ThePeopleOfTheSun]

Is this the guy who does the Titanium Physicist podcast? Sounds just like him.