How to evaluate an expression with variables | Introduction to algebra | Algebra I | Khan Academy

Learn how to evaluate an expression with variables using a technique called substitution (or "plugging in").

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Algebra I on Khan Academy: Algebra is the language through which we describe patterns. Think of it as a shorthand, of sorts. As opposed to having to do something over and over again, algebra gives you a simple way to express that repetitive process. It's also seen as a "gatekeeper" subject. Once you achieve an understanding of algebra, the higher-level math subjects become accessible to you. Without it, it's impossible to move forward. It's used by people with lots of different jobs, like carpentry, engineering, and fashion design. In these tutorials, we'll cover a lot of ground. Some of the topics include linear equations, linear inequalities, linear functions, systems of equations, factoring expressions, quadratic expressions, exponents, functions, and ratios.

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[konglee]

when will i ever use this in my life time...? just doing this for school.

[hellowhatsup]

Khan is so much better than my textbook at explaining things. Simple and straight to the point. Always come here to see if they have a video on what I don't understand or right before a test. Works miracles.

[juliecho]

When a 2 minute video is more helpful than a 40 min lesson at school

[Ymv]

thanks this helped me cuz i dont know what the variable is used for

[nitronick]

now I'm not stupid and can do my homework!!!!

[paulocleon]

It's important to make clear STH like this: each ticket cost = 5; Total taxes –whatever the case– are always going to be = 3 (not one per ticket, rather one for each participation in the raffle).

[naifnuwisser]

IAM 10 AND I AM TAKI NG THIS IN SCHOOL

[kaidenwilliams]

how do u find out what the letter is equal to?

[okidokes]

ok thank you we had to stop the test we where doing and i forgot how to do this question thank very much you saved my life now i can become a animator or a youtuber or in the military or hitman

[Jay-nqog]

Let’s be real ur only here cause your teacher made watch this

[aronsherman]

First of all, nobody cares. Second of all, this is not a boring video. It's good to watch if you want to go anywhere in life and be successful. If you want to hate go to bettervidsthensmosh's channel and vent it all out there.

[felinoire]

Thanks! This will help me to my math quiz tomorrow!!

[hacoballen]

Hey Whats up i would like to know what software you used to make and draw this video?

Thnx

[whosab]

Can you answer this
2xy^2z if x=3 y=2 z=-1

[sqwush]

Can anyone explain why his cursor looks like a crosshair?

[dogensuch]

We now what's happening, everyone is doing school work

[nitronick]

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[reedlam]

FYI my teach made me watch this(super boring) video (LOL)