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Math Help - Some function problems.

  1. #1
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    Some function problems.

    'Kay, doing college algebra, I've done most of these myself but I'm stuck on these. My teacher sadly doesn't have help time whenever I'm out of class. If I could get an explanation, that would be great. The book doesn't help, it just gets very technical with math terminology when I'm already very bad at it, lol.

    4.Using the function, f(x)=8-x, find the following.
    a)f(x+h)
    b)f(x+h)-f(x)
    c)f(x+h)-f(x)
    ------------
    h
    I know, for example f(x+h)-f(x) using f(x)=5-x was -h, but I don't understand how its simplifies to just one letter. =/

    10.Find (f o g)(x) and (g o f)(x) [That o is that really small circle symbol I don't have a key for.]
    f(x)=10x-1, g(x)=8-4x.

    11.For the given functions, find (f o g)(x) and (g o f)(x) and the domain of each.
    f(x)=3x+1, g(x)=square root of x
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  2. #2
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    Re: Some function problems.

    for 10 . substitute x in f(x) as 8-4x and x in g(x) as 10x-1
    thats the way u find composite of fn
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  3. #3
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    Re: Some function problems.

    Quote Originally Posted by Leki View Post
    'Kay, doing college algebra, I've done most of these myself but I'm stuck on these. My teacher sadly doesn't have help time whenever I'm out of class. If I could get an explanation, that would be great. The book doesn't help, it just gets very technical with math terminology when I'm already very bad at it, lol.
    I'm not clear exactly what your question is.

    4.Using the function, f(x)=8-x, find the following.
    a)f(x+h)
    You know what "f(x)= 8- x" means don't you? f(a)= 8- a, f(y)= 8- y, and f(x+ h)= 8- (x+ h)

    b)f(x+h)-f(x)
    So f(x+ h)- f(x)= 8+ (x+ h)- (8+ x). Simplify by clearing the parentheses.

    [quote]c)f(x+h)-f(x)
    ------------
    h[/quot
    [tex]\frac{f(x+h)- f(x)}{h}= \frac{8+ (x+h)- (8+ x)}{h}

    I know, for example f(x+h)-f(x) using f(x)=5-x was -h, but I don't understand how its simplifies to just one letter. =/
    f(x+ h)- f(x)= (5- (x+h))- (5- x). Simplify that.

    10.Find (f o g)(x) and (g o f)(x) [That o is that really small circle symbol I don't have a key for.]
    f(x)=10x-1, g(x)=8-4x.
    Do you know what "f o g" means? What is its definition?

    11.For the given functions, find (f o g)(x) and (g o f)(x) and the domain of each.
    f(x)=3x+1, g(x)=square root of x
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