username3526710
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#1
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Can anyone help me with functions? I don't get them at all. I would really appreciate it. Thank you.
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RDKGames
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#2
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(Original post by SyncIn)
Can anyone help me with functions? I don't get them at all. I would really appreciate it. Thank you.
What exactly is the issue?
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username3526710
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#3
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(Original post by RDKGames)
What exactly is the issue?
I just don't get them. Not even fg(x). Can you explain please?
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JustforAma
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#4
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fg(x) are functions, meaning, you can put any number of x into it, and it will spit out a number. When you have something like fg(x), its essentially a function inside a function. But don't think too much on that, because when it gets to fghhfgh(x), youll get confused.

Let's say
f(x) = 2x + x^2
g(x) = x+3
Now fg(x) means you're putting g into f, if it was fgh(x), you're putting h into g, then all that into f. Always right to left (just for convention, no real reason). Now algebraically, to solve this, you put g into f. How?

You're gonna take all of g, and wherever you see x, you're gonna replace it with all of g. So

fg(x) = 2(x+3) + (x+3)^2. All you've done is, replace x with whatever g(x) equalled. Brackets are important. Usually clean it up, to get the final marks.
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RDKGames
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(Original post by SyncIn)
I just don't get them. Not even fg(x). Can you explain please?
fg(x) is shorthand notation for f(g(x)) which means you take your function g(x) and substitute it into f(x) by replacing every x with whatever g(x) is. What's confusing about this?
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username3526710
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#6
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(Original post by RDKGames)
fg(x) is shorthand notation for f(g(x)) which means you take your function g(x) and substitute it into f(x) by replacing every x with whatever g(x) is. What's confusing about this?
Can you give an example?
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RDKGames
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(Original post by SyncIn)
Can you give an example?
One was given in post #4 but here's one:

f(x)=x+2
g(x)=\sin(x)

fg(x)=\sin(x)+2
gf(x)=\sin(x+2)
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username3526710
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Can you give me a simple question. I will try it.
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RDKGames
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(Original post by SyncIn)
Can you give me a simple question. I will try it.
Given that f(x)=x^2+1 and g(x)=\frac{x}{2} determine the expressions for fg(x) and gf(x) hence find the values of fg(2) and gf(0)
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username3526710
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(Original post by RDKGames)
Given that f(x)=x^2+1 and g(x)=\frac{x}{2} determine the expressions for fg(x) and gf(x) hence find the values of fg(2) and gf(0)
Never mind, I'll just go on youtube.
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username3526710
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#11
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And sorry for the hassle
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