# Maths - what does f(x) mean?

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#1
I need to know what f(x) means and why we use it in maths? I'm really stuck.
0
16 years ago
#2
'function of x'
f(x) basically means y, and f'(x) means dy/dx
The x can have a value, so for example, f(x) = 2x + 1, then f(1) = 3

that is as good as I can explain it!!!
3
16 years ago
#3
O, and f(x) is the 'range' (range and domains come in at A2 (ocr spec.))
0
16 years ago
#4
f(x) is just something that is done to "x", its a function
1
16 years ago
#5
(x) is the basic equation of the graph, say, x² + 4x +4.

The F is what you are doing to it, eg translating it up 2, or stretching it etc. There are equations for this but I've forgotten them!
0
16 years ago
#6
(Original post by gordon2002)
'function of x'
f(x) basically means y, and f'(x) means dy/dx
The x can have a value, so for example, f(x) = 2x + 1, then f(1) = 3

that is as good as I can explain it!!!
Tbh thats about as good as most people would be able to do and i didnt know that f'(x) was dy/dx
0
16 years ago
#7
remember the little function boxes you did when you were like 10. x goes in, f(x) comes out. the function could be, say, adding 5, dividing by two... whatever.
1
16 years ago
#8
(Original post by heninacoop)
(x) is the basic equation of the graph, say, x² + 4x +4.

The F is what you are doing to it, eg translating it up 2, or stretching it etc. There are equations for this but I've forgotten them!
Completely wrong. As Chewwy says, x goes in, f(x) comes out. You can use g(x), h(x), Ø(x), Ω(x), Bob(x), Ostrich(x), anything you like. The letter, symbol or even word before the (x) is simply a way of allowing you to know which function it is you are talking about. You can define f(x) to be anything you like, the "f" label is irrelevant of what the function is.

The letter within the brackets is the variable. You can have multiple variables too, like f(x,y), H(x,y,t) or anything you like really (but not repeated letters!).
1
16 years ago
#9
f(x) is the gradient function isnt it? you use it to find gradients using differentiation?
0
16 years ago
#10
(Original post by PIPSarah)
f(x) is the gradient function isnt it? you use it to find gradients using differentiation?
0
16 years ago
#11
remember the little function boxes you did when you were like 10. x goes in, f(x) comes out. the function could be, say, adding 5, dividing by two... whatever.
That's great you deserve some rep I've been having trouble understanding this.
0
16 years ago
#12
(Original post by chanandler)
I need to know what f(x) means and why we use it in maths? I'm really stuck.

f(x) just means a 'function' of 'x',
0
4 years ago
#13
i need help
0
4 years ago
#14
I'm Korean high school student.and i have more questions after reading all the replys...f(x) means function basically as we all learned...but when we think about the polynomial,the question says 'the polynomial f(x)=3x 4....'I want to ask that f(x)'s meaning...
0
3 years ago
#15
If f(x+4)=4x then find f(x)?
Can anyone explain how its done?
0
3 years ago
#16
(Original post by Galibmehedijami)
If f(x+4)=4x then find f(x)?
Can anyone explain how its done?
I may be wrong but what you want to do is to do the reverse of the change in the input x. Eg. in this function it shows that 4 is added to the input as shown with f(x+4) but to get f(x), you do the opposite so subtract 4 to get back to the original input, x. Therefore you get f((x+4) - 4) which is f(x) as +4-4 is 0. Thus with the 4x, the x here would be substituted for (x-4) which results with 4(x-4) and if you expand that, you get 4x-16. So f(x)=4x-16.
0
2 years ago
#17
Ya me to can someone help us
0
2 years ago
#18
But how I am still confused how does it become a 3
0
2 years ago
#19
What do u mean by f means functions
0
2 years ago
#20
It is a functions question where you have to substitute
0
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