# What is the domain of a function? | Functions | Algebra I | Khan Academy

What is the domain of a function? | Functions | Algebra I | Khan Academy

Sal introduces the concept of “domain” of a function and gives various examples for functions and their domains.

Watch the next lesson: https://www.khanacademy.org/math/algebra/algebra-functions/domain-and-range/v/range-of-a-function?utm_source=YT&utm_medium=Desc&utm_campaign=AlgebraI

Missed the previous lesson?

https://www.khanacademy.org/math/algebra/algebra-functions/domain-and-range/v/introduction-to-interval-notation?utm_source=YT&utm_medium=Desc&utm_campaign=AlgebraI

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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your videos help so much! i am currently learning reflections of exponential functions and this really helps.

I’m so surprised that I easily understood these!! Your videos are amazing and really helpful:) thank you!

5:04 no…still nope…

my college literally uses khan academy instead of actual classes 😀

Oh sure, you upload this AFTER I failed a quiz miserably. Several weeks ago.

5:04 hopefully

thanks

how is it that greater than or equal to 6 is considered negative when the equation is y -6 ?

3:14, does someone in the background laugh at "double stroke"? Obviously asking the important questions here.

This looked really cryptic but it’s actually easy.

THANK YOU SO MUCH , IT WAS VERY HELPFUL

Good math 🏖️🗺️😉

You’re the man, very clear explanation

First to comment

this is really helpful

I am thoroughly impressed by his mouse handwriting. lol

Nice video & explanation !!!

I took a test at Algebra 1 on functions and I got an 85 on my exam. Thank you so much.

I still don’t understand this. I don’t know what’s wrong with me for not getting it. 🙁

Am helped 🙂. Thank you

for your example g(y)= the square roots of y-6. would interval notation look like [6, infinity) ?

float func(float x) {

float ret;

return ret = (x) ? 2.0/x : 0.0;

}

He: And it starts to make sense

Me: no

Ive bern going through notes trying to remember this and you post it the day BEFORE my math final . God bless you 😂

Thank you

Ok…I don’t know if I finally lost it or not BUT Is there any audio in this video or not?

Khan Academy teaches better than my teacher

I did not pick up on this but the Domain is the Y right? and that would make Range the X?

I’m sorry, as much as I like Khan Academy, this video sucks. Just jumping into set notation doesn’t seem to have any purpose other than convincing students they will never understand math.

isnt square root of 2 undefined, so that the in the domain of g(y) y is different than 8?

Sir i do no speak smart math language

First

I still don’t understand it

Can you speak normal math language for dumb people

Thnx alot sir.. Realy it helps me alot to understood and find the domain of a function… Tysm sr.. ❤❤

Why can’t domain have negative no.s

Khan academy, could u guys make more vids like this? It’s great for studying for ap

This is the longest video ever uploaded to YouTube

شكراً يا أستاذ خان 🌹

what will be the domain of f ( x ) = 1/ sqrt ( x^2 – 1 )