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    • Thread Starter
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    Here how I did and never get it correct...

    h(x) = 3x - 2
    h(x + 1)

    x + 1 = 3x - 2
    (-1) (-1)

    x = 3x - 3 it says 3x - 1 is the answer...

    --------------------------------------------------------------------------

    f(x) = x^2 + 5x - 1
    f(3x)

    3x = x^2 +5x -1
    the answer was 9x^2 + 15x - 1 and I can't get my head around this one at all.


    Does anyone understand these questions and help me out? Thanks.
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    You're not meant to solve an equation like that, wherever x is you instead put x + 1 in the first case and in the second case wherever x is you instead put 3x
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    Hi there, could you write out exactly what the question is?
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    (Original post by ckfeister)
    Here how I did and never get it correct...

    h(x) = 3x - 2
    h(x + 1)

    x + 1 = 3x - 2
    (-1) (-1)

    x = 3x - 3 it says 3x - 1 is the answer...

    --------------------------------------------------------------------------

    f(x) = x^2 + 5x - 1
    f(3x)

    3x = x^2 +5x -1
    the answer was 9x^2 + 15x - 1 and I can't get my head around this one at all.


    Does anyone understand these questions and help me out? Thanks.
    Can you post a picture of the question? Thanks.
    • Thread Starter
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    (Original post by Ollie231213)
    Hi there, could you write out exactly what the question is?
    (Original post by Hydeman)
    Can you post a picture of the question? Thanks.
    First question.
    h(x) = 3x - 2

    Work out expressions, giving answers in the simplest form.
    ii) h(x+1)

    Second question.
    f(x) = x^2 + 5x - 1

    Work out expressions, giving answers in simplest form.
    i) f(3x)

    Topic* is function notation.
    • Community Assistant
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    Replace any x with what's in the bracket.

    (Original post by ckfeister)
    First question.
    h(x) = 3x - 2

    Work out expressions, giving answers in the simplest form.
    ii) h(x+1)

    Second question.
    f(x) = x^2 + 5x - 1

    Work out expressions, giving answers in simplest form.
    i) f(3x)

    Topic* is function notation.
    Replace any x with what's in the bracket.
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    (Original post by ckfeister)
    First question.
    h(x) = 3x - 2

    Work out expressions, giving answers in the simplest form.
    ii) h(x+1)

    Second question.
    f(x) = x^2 + 5x - 1

    Work out expressions, giving answers in simplest form.
    i) f(3x)

    Topic* is function notation.
    Like a number machine, "f(x)" and "h(x)" are functions with an input of whatever is in the bracket.

    So if h(x) = 3x - 2, it means take whatever x is, multiply by three, and subtract two.

    If the input is "x+1", however, it means add one to x first, then multiply by three, then subtract two.

    So h(x+1) = 3(x+1) -2
    = 3x +3 -2
    = 3x +1
    • Thread Starter
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    (Original post by Ollie231213)
    Like a number machine, "f(x)" and "h(x)" are functions with an input of whatever is in the bracket.

    So if h(x) = 3x - 2, it means take whatever x is, multiply by three, and subtract two.

    If the input is "x+1", however, it means add one to x first, then multiply by three, then subtract two.

    So h(x+1) = 3(x+1) -2
    = 3x +3 -2
    = 3x +1
    Oh now I get it, thanks.
 
 
 
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