Evaluating expressions where individual variable values are unknown | Algebra I | Khan Academy

Working through a few examples where we need to evaluate an expression, but we don't know the individual variable values

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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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[andreai]

"This big hairy thing" can't stop laughing! I LOVE KHAN ACADEMY so much!!

[SunOfRa]

Only mathematics videos worth watching at 1:07 am on a Saturday morning lol. This is awesome! Saving my ass before Linear Algebra/Matrices start!

[skilltholaggins]

I've seen multiple anecdotes that people start looking at other videos/books when they get to khan academy's algebra sections. I've figured out why: You've left out SADMEP!

[Ragamuffyn]

Then you want to see how many of them you are able to take out. You have a combination of mines a+b+c which are able to take out one of them a+b+c = -1. So one soldier.

Then you can just solve any equation to find this out. There's obviously more factors, but that's just an example I could come off with off the bat.

[carsonstorm]

ok. this is an awesome video. learned a lot. things khan academy. omg I sounds like a nerd. haahahhahaha

[Ragamuffyn]

Lets say you are in the military facing an enemy. You want to know how many soldiers they have. You know from previous intel that if you see one lieutenant and one sergeant they always go along with 5 others so they are 7 in total which accounts for the x+y=7. So for every pair of them which you see, you know how many soldiers they have without having to calculate every individual.

[kidinkdjillwill]

i find this easy, cuz lets say for the first one so you have 7 and what three numbers add up to seven, 3+2+2 or 3+3+1, so the the first becomes 15+10+10=35 AND SECONF 15+15+5=35, or you can just times the number 5 with the answer, and ik he says thaat, but i figured it out like 20 sec, so now the question is for which'grade is this for

[healthyamerican]

the colorful ink is not always easy to see. wish you would use black and white and keep it simple

[woo]

study engineering in university and you will find the answer to your question.