Introduction to rational and irrational numbers | Algebra I | Khan Academy

Learn what rational and irrational numbers are and how to tell them apart.

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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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[rin-sdql]

Thx you teach better than my real math teacher

[ghufranahmed]

My teachers at school made me learn for years but still i failed in this topic
Today morning I watched this
Wow i passed!
Love you Khan Academy
so great!
I don't have words, I am so happy
Thanks!

[newt]

Numbers.... Iiiiirrational
X)
XD
I love how he says it! XD lol.

[rubyyxlc]

3:41 Irrational numbers, my timestamp for future reference

[teendailymotivation]

Khan: " Today were gonna learn about rational numbers... rational numbersss.."

Student: "Okay I get it rational num- "

Khan: " Rational numberss... rationallll numbers..."

[Y-th]

Who is just looking down in the comments while there watching the video 😝 maybe it is just me okay 👌🏻

[ColtixOG]

10yrs later and ur still teaching me new things. Thank you for being in my life as an ACCUAL teacher

[imbaka]

I feel like teachers in school most of the teachers really are confusing and don't explain well youtube has helped me a LOT in math and I really thank khan academy for helping me :)

[rasbanikaur]

Rational numbers are ratios of integers, including decimals with patterns. Irrational numbers, like pi and the square root of2, never terminate or repeat. There is always an irrational number between any two rational numbers, and the sum or product of an irrational and rational number is also irrational.

[00:00] Rational numbers are ratios of integers, including non-integers like 3.75, which can be represented as 375/100 or 15/4.
- Integers are rational numbers
- Non-integer rational numbers can be represented as the ratio of two integers
- Examples of non-integer rational numbers include 3.75, which can be represented as 375/100, 750/200, or 15/4

[01:56] Rational numbers can be represented as the ratio of two integers, but some famous numbers in mathematics are not rational.
- Rational numbers can be expressed as a fraction of two integers
- Repeating decimals can also be represented as the ratio of two integers
- Some famous numbers in mathematics, such as pi, are not rational

[03:47] Irrational numbers are exotic but not uncommon, with an infinite number between any two rational numbers.
- There is always at least one irrational number between any two rational numbers
- Taking the square root of any non-perfect square or adding an irrational and a rational number results in an irrational number

[-DiveForIve-]

00:05 Definition of rational numbers
01:03 Understanding rational and irrational numbers
02:00 Rational and irrational numbers can be represented as the ratio of two integers or repeating decimals.
02:36 Representation of repeating decimals as ratios of integers
03:18 Rational numbers include integers, finite non-repeating decimals, and repeating decimals.
04:12 Irrational numbers never terminate and never repeat.
04:46 There is always an irrational number between any two rational numbers.
05:25 Understanding the properties of irrational and rational numbers

[mattpeirce]

😂I watched this 15 times in a row because my math regents are tomorrow

[monazcoolirani]

i think the khan academy dudes voice is close to Morgan freeman's

[royaleplayzyt]

Is it just me or is Sal's voice soooo calm!

[suhebkhan]

FANTASTIC WAY OF TEACHING SIR... AWESOME

[DuckSquad]

I'm glad the "PAUSE" button is here so people can "pause" the video whenever they like and have a look at what the person in the video is trying to teach so they can stop and have a think about it!

[miasims]

I still can’t really understand it, but I just needed to know how do you get a irrational number.. so thanks 🙃

[EZ-kqxj]

POV: you have a test tomorrow and you ARE NOT READY

[tableswithoutchairs]

i had 2 choices, watch a video my teacher sent me that explains to me the exact same thing, but takes 16 minutes, or watch this. and of coarse i chose this! this is really helpful

[mr.trollge]

I like these types of videos, not because of the math, but because they way he writes perfectly with that writer

[themecha]

Thanks khan academy... today at school we were learning Zeno's paradox and I could not understand it. Now after watching this amazing video, I am happy to say that now I understand it