# Difference between f(x) and g(x)

• Apr 30th 2011, 01:19 PM
gobblewobble123
Difference between f(x) and g(x)
I was wondering what the difference between f(x) and g(x) was. I've seen f(x) used in quadratic equations, etc and understand it as being a more efficient notation than using y. I don't know what g(x) is though. I'm guessing that it may be a notation for z?

• Apr 30th 2011, 01:27 PM
SpringFan25
the letter which you use to label a function has no special meaning. g(x) just identifies a function of x, in the same way as that f(x) does.

Using a "g" instead of an "f" only means the function has a different label assigned to it. Typically this is done where you have already got an f(x), so creating another one would be confusing.

you can use any letter you like (i wouldn't use x, though):

eg:
f(x) = 2x+1
g(x) = 100x^2
r(x) = 10+6x

Now, we could have called all of those f(x), but it woudl get pretty confusing if you ever had a problem involving more than one of those at a time!
• Apr 30th 2011, 01:29 PM
Plato
Quote:

Originally Posted by gobblewobble123
I was wondering what the difference between f(x) and g(x) was. I've seen f(x) used in quadratic equations, etc and understand it as being a more efficient notation than using y. I don't know what g(x) is though. I'm guessing that it may be a notation for z?

What is the difference between the words 'Frank' and 'George'?
That is the same as the difference between \$\displaystyle f(x)~\&~g((x)\$.