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Staredit Network -> Miscellaneous -> Math Question
Report, edit, etc...Posted by Kame on 2005-03-15 at 21:15:10
so f{x} is another term for 'y' right?

so if y = 5
than the f{x} = 5
but that doesn't mean that
x = 5, right?

Where's the relationship?
Report, edit, etc...Posted by chuiu on 2005-03-15 at 22:15:24
You will start using this when they ask you to do stuff like f(x-5), etc and the x variable comes from a preset variable or a variable from another equation.
Report, edit, etc...Posted by LegacyWeapon on 2005-03-15 at 22:18:25
For any number x, f(x) = 5 meaning whatever number x is, f(x) is 5.
f(9) = 5
f(1969) = 5

f(x) = y
Report, edit, etc...Posted by CheeZe on 2005-03-15 at 22:30:51
"f" is used because it stands for function. Remeber back in the days, when people tried to teach you algebra by presenting you with machines? each "function" (or f(x)) is like that machine, where x is the variable that goes in the function and the function representing an equation.
Report, edit, etc...Posted by Staredit.Net Essence on 2005-03-15 at 22:58:08
Painful memories...
Report, edit, etc...Posted by DT_Battlekruser on 2005-03-16 at 00:47:53
How dare you insult the noble institution of math! *slap* tongue.gif

Yeah for simpletons like you f(x)= essentially replaces y= in equations you graph.
Report, edit, etc...Posted by ShadowBrood on 2005-03-16 at 03:04:17
F(X) doesnt Y
F(X) Is Y but in a different statement.

God I'm so tired to elaborate but it is used in calculus in the place of Y because nearly all of calculus in function which is what F(X) is, a function notation.
Report, edit, etc...Posted by DT_Battlekruser on 2005-03-16 at 11:13:32
I said essentially the same. Try not to confuse her wink.gif
Report, edit, etc...Posted by Clokr_ on 2005-03-16 at 11:33:41
QUOTE(DT_Battlekruser @ Mar 16 2005, 05:13 PM)
I said essentially the same.  Try not to confuse her wink.gif
[right][snapback]166139[/snapback][/right]


Its not essentially the same... f(x) is not y.

Well, first of all, this is related to polynomials. A polynomial can be really long, so if you have to write it a lot of times it would be a pain, so you can just give a name to it. To give a name you use a letter and, between brackets, you put the variables that it uses. Examples:

CODE
x + 2  -> p(x)
x³ + (2/3)x² - 3/4 -> q(x)
y² + 5x³y - (5/4)x² - 5y + 2x/3 -3 -> m(x, y)


Now, the functions have this form:

polynomial = y
like x³ + 3x² - 5y + 4 = y

But since it has a polynomial, a function can be really long, and it would be a pain, so you can just give a name to the polynomial. For that, the standar is use the letter 'f', from 'function':

CODE
x + 3 = y -> f(x) = y
x² - 3x + 1/2 -> f(x) = y
50x³ - (5/4)x² - 3x/7 + 1/2 -> f(x) = y


Report, edit, etc...Posted by (U)Bolt_Head on 2005-03-16 at 11:42:21
Lets see what i remember.

for ƒ{x}=5 you have a horizontal line crossing though the Y axis at 5.
So for any value of X the result will be 5.

ƒ{x} is like a way of saying y. But if there is a value in the box (like firebolt pointed out) is indicating like value of X you want returned.

Heres and example.
ƒ{5} = 2x

Your basic equation is y = 2x
ƒ{5} basicly asks "what is the value of Y when X is equal to 5?"
the answer being 10 as seen below
Y = 2(5)

Another Example.
ƒ{10} = 5x+3

y = 5(10)+3
y = 50+3
y = 53


ADDITION:
Crap clokr_ replied before me and hes smarter than me so now i look dumb.
EDIT:
Oh, i doubt she is doing all that Clokr_ *Time for bolt_head to shut up*
Report, edit, etc...Posted by chuiu on 2005-03-16 at 12:01:44
I thought I explained it just fine in my post. I mean ... look at her sig. tongue.gif
Report, edit, etc...Posted by Kame on 2005-03-16 at 12:33:42
don't diss the sig! it rocks! cool1.gif

so what is the difference between an equal sign '=' and an arrow '->' ?
Report, edit, etc...Posted by DT_Battlekruser on 2005-03-16 at 18:38:27
QUOTE(Clokr_ @ Mar 16 2005, 08:33 AM)
Its not essentially the same... f(x) is not y.

Well, first of all, this is related to polynomials. A polynomial can be really long, so if you have to write it a lot of times it would be a pain, so you can just give a name to it. To give a name you use a letter and, between brackets, you put the variables that it uses. Examples:

CODE
x + 2  -> p(x)
x³ + (2/3)x² - 3/4 -> q(x)
y² + 5x³y - (5/4)x² - 5y + 2x/3 -3 -> m(x, y)


Now, the functions have this form:

polynomial = y
like x³ + 3x² - 5y + 4 = y

But since it has a polynomial, a function can be really long, and it would be a pain, so you can just give a name to the polynomial. For that, the standar is use the letter 'f', from 'function':

CODE
x + 3 = y -> f(x) = y
x² - 3x + 1/2 -> f(x) = y
50x³ - (5/4)x² - 3x/7 + 1/2 -> f(x) = y

[right][snapback]166152[/snapback][/right]



Yes, I know. I was trying not to be complicated for god's sake.
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