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.

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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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1. Das Crazy on August 30, 2021 at 9:43 pm

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

2. marg rette on August 30, 2021 at 9:47 pm

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

3. Skyona Sisters on August 30, 2021 at 9:49 pm

5:04 no…still nope…

4. Superpants on August 30, 2021 at 9:51 pm

5. Chibi Prussia on August 30, 2021 at 9:55 pm

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

6. Rafa on August 30, 2021 at 9:55 pm

5:04 hopefully

7. Tajender Singh on August 30, 2021 at 9:57 pm

thanks

8. The_GhOst_Eater on August 30, 2021 at 9:58 pm

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

9. goodcleanfun on August 30, 2021 at 10:03 pm

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

10. ossobuco on August 30, 2021 at 10:04 pm

This looked really cryptic but it’s actually easy.

11. Fady Hameed on August 30, 2021 at 10:07 pm

THANK YOU SO MUCH , IT WAS VERY HELPFUL

12. Hebeli Haguna on August 30, 2021 at 10:10 pm

Good math 🏖️🗺️😉

13. Riccardo on August 30, 2021 at 10:10 pm

You’re the man, very clear explanation

14. Luke Joseph on August 30, 2021 at 10:11 pm

First to comment

15. Justin Wilborn on August 30, 2021 at 10:11 pm

16. Alexis W on August 30, 2021 at 10:11 pm

I am thoroughly impressed by his mouse handwriting. lol

17. CHINMAY ACADEMY on August 30, 2021 at 10:14 pm

Nice video & explanation !!!

18. DYLAN HERNANDEZ on August 30, 2021 at 10:14 pm

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

19. Miguel Martinez on August 30, 2021 at 10:16 pm

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

20. Peterson PixesKE on August 30, 2021 at 10:16 pm

Am helped 🙂. Thank you

21. Maritza Soto on August 30, 2021 at 10:16 pm

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

22. Crud O'Matic on August 30, 2021 at 10:17 pm

float func(float x) {
float ret;
return ret = (x) ? 2.0/x : 0.0;
}

23. BercaRStone on August 30, 2021 at 10:17 pm

He: And it starts to make sense

Me: no

24. CAGEtheDM on August 30, 2021 at 10:18 pm

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

25. Curiosity Squared on August 30, 2021 at 10:20 pm

Thank you

26. Tropixs on August 30, 2021 at 10:21 pm

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

27. Maahi Islam on August 30, 2021 at 10:21 pm

Khan Academy teaches better than my teacher

28. Axelrod on August 30, 2021 at 10:22 pm

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

29. NCARalph on August 30, 2021 at 10:24 pm

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.

30. Vinícius Magalhães Horta on August 30, 2021 at 10:25 pm

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

31. YoBoi21 XD on August 30, 2021 at 10:26 pm

Sir i do no speak smart math language

32. Ben B on August 30, 2021 at 10:26 pm

First

33. X.celestia .X on August 30, 2021 at 10:28 pm

I still don’t understand it

34. YoBoi21 XD on August 30, 2021 at 10:29 pm

Can you speak normal math language for dumb people

35. calliagraphy with shafaque on August 30, 2021 at 10:29 pm

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

36. Ragini Kumar on August 30, 2021 at 10:30 pm

Why can’t domain have negative no.s

37. Robert Yun on August 30, 2021 at 10:33 pm

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

38. Josh K on August 30, 2021 at 10:34 pm