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# What is the f(x) notation? watch

1. Hi,

I would appreciate it if someone could explain what the significance and use of the 'f of x' notation is, particularly in graphs?
Is it just an alternative way of writing 'y' in e.g. y=2x+9?

Thanks
2. (Original post by AKRYL)
Hi,

I would appreciate it if someone could explain what the significance and use of the 'f of x' notation is, particularly in graphs?
Is it just an alternative way of writing 'y' in e.g. y=2x+9?

Thanks
means 'function of x'

You are correct in saying that an alternative of
is

you can use anything;

etc
3. (Original post by edothero)
means 'function of x'

You are correct in saying that an alternative of
is

you can use anything;

Unparseable or potentially dangerous latex formula. Error 6: Image was not produced or one of its dimensions is too small.
\
etc
Can you elaborate on what you mean by 'function of x'?
4. (Original post by AKRYL)
Hi,

I would appreciate it if someone could explain what the significance and use of the 'f of x' notation is, particularly in graphs?
Is it just an alternative way of writing 'y' in e.g. y=2x+9?

Thanks
Yeah, pretty much, f of x means function of x as someone else said previously.

It means that your rule that maps is a function/rule that sends your value to another value using a certain rule.

With this, you can then see that is a function of and so is a constant, or other such subtleties.
5. (Original post by AKRYL)
Can you elaborate on what you mean by 'function of x'?

essentially means, when goes in, comes out

Its a function with a set 'criteria' if you'd like.

For this particular function:

As input goes in, it gets multiplied by 2, followed by an addition of 9, then outputs

So when ,

Like I said before, this could easy be which again represents 'g is a function of x'
Don't be thrown off by the .
6. (Original post by Zacken)
Yeah, pretty much, f of x means function of x as someone else said previously.

It means that your rule that maps is a function/rule that sends your value to another value using a certain rule.

With this, you can then see that is a function of and so is a constant, or other such subtleties.
So is '2x+9' the rule that is applied to the value contained within the brackets of f(x) in order to give you the value of y?
7. (Original post by edothero)

essentially means, when goes in, comes out

Its a function with a set 'criteria' if you'd like.

For this particular function:

As input goes in, it gets multiplied by 2, followed by an addition of 9, then outputs

So when ,

Like I said before, this could easy be which again represents 'g is a function of x'
Don't be thrown off by the .
So is '2x+9' the rule or set of instructions that is applied to the value contained within the brackets of f(x) ,in order to give you the value of y?
8. (Original post by AKRYL)
So is '2x+9' the rule that is applied to the value contained within the brackets of f(x) in order to give you the value of y?
Yes, that is correct

The is applied to the input.

So for example

So you would know that when ,
And you can plot that easily.
9. (Original post by AKRYL)
Hi,

I would appreciate it if someone could explain what the significance and use of the 'f of x' notation is, particularly in graphs?
Is it just an alternative way of writing 'y' in e.g. y=2x+9?

Thanks
f(x) notation essentially shows the input value for x (or whatever letter chosen to represent the variable of the equation)
E.g.
y=x+69
f(-4)=-4+69-->when x=-4, y=65
10. (Original post by edothero)
Yes, that is correct

The is applied to the input.

So for example

Ok, but what does the 'f' part of 'f(x)' represent?
Also, why is that when you write the equation of a curve, using this notation, you have to write the part highlighted in bold y=f(x)=2x+3 and not simply f(x)=2x+3?
11. (Original post by AKRYL)
Ok, but what does the 'f' part of 'f(x)' represent?
Also, why is that when you write the equation of a curve, using this notation, you have to write the part highlighted in bold y=f(x)=2x+3?
Nothing important , its just a way of labeling the function.

You could do

It all means the same thing.
12. (Original post by AKRYL)
Ok, but what does the 'f' part of 'f(x)' represent?
Also, why is that when you write the equation of a curve, using this notation, you have to write the part highlighted in bold y=f(x)=2x+3 and not simply f(x)=2x+3?
The function. What everyone else has been trying to explain.

The is just the name of the function you could use any letter instead of f to indicate a different function, where you have two. So and
13. (Original post by AKRYL)
Ok, but what does the 'f' part of 'f(x)' represent?
Also, why is that when you write the equation of a curve, using this notation, you have to write the part highlighted in bold y=f(x)=2x+3 and not simply f(x)=2x+3?
To clarify further, f is the function and we write f(x) to be the value of the function at x. So technically f(x) isn't the function it's the value of the output of the function when the input is x.
14. Correct me if I'm wrong but a function is like a rule which affects any value of the independent variable (which is x here).

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