# What Is A Function? | Functions And Their Graphs | Algebra II | Khan Academy

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## 23 thoughts

1. Ryan Hewett says:

Why is an input for a graph measurement not considered a function if it produces 2 outputs?

2. Ryan Hewett says:

My reasoning in my mind for asking the question that I am asking below is that a function definition follows on definitions such as dictionary.com as follows: Mathematics.
Also called correspondence, map, mapping, transformation. a relation between two sets in which one element of the second set is assigned to each element of the first set, as the expression y = x 2; operator.
Also called multiple-value function. a relation between two sets in which two or more elements of the second set are assigned to each element of the first set, as y 2= x 2, which assigns to every x the two values y = + x and y = − x.
a set of ordered pairs in which none of the first elements of the pairs appears twice.

3. Gustavo Woltmann says:

It’s very good explanation of a function. I like these useful videos.

And then Satan said, “I have an idea, let’s put numbers in Math!”

5. Ryan Richards says:

i need to know the name of the speaker for a math essay on functions pleas help as soon as posible

6. doge mlg says:

hi

7. Munir Koro says:

this will help with my upcoming exam

8. George Fan says:

He has taught me more in 3 months that my school in a year.

9. Keep Scratching says:

How do you know it’s even or odd???

10. Shely Fi says:

Mental
Abuse
To
Humans

11. LemonHairG says:

Fuck my life, i am gonna fail in life, because i don’t know this bullshit

12. Revilo 366 says:

Who else is watching the day before their test

13. Andella Hypolite says:

How was the equation of the circle derived?

14. Flying_Hippos Derp says:

I have two teachers…. and y’know what, you’re better than both of them! (I think, the one I like is exceptionally good and he used to be a professor in a University)

15. Flying_Hippos Derp says:

Dear x,
Shes never coming back

Signed FlyingHippos_Derp

16. Arian zamin says:

when f(2)=3 !!!!!!! 😨😨😨 wtf its not 3 its 4

17. more like a banana says:

I get it, I get it all, I feel so genius

18. Abhyuday Tewari says:

y> x is not a function

19. steve levario says:

Thank you!

20. ieangzorng lim says:

could anyone explain me? during 7:00 why does X associate with Y?

21. enfakkingee says:

I khan’t function

22. MinerFreakPVP says:

Doesn’t this go towards programming?

23. Jesus Siyanda says:

Great video