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    "f(x) = 2x + c
    g(x) = cx + 5
    fg(x) = 6x + d
    c and d are constants.
    Work out the value of d. "

    I've done the first two steps to get to 2cx+10+c... but I'm not quite sure what to do next. I'm guessing you make that equal to 6x+d but I don't know what to do after that.

    Help would be appreciated, cheers.
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    I recognise this as a MyMaths question.

    Think of it more simply...

    6 = 2 * ?

    Then, once you have worked out the value of c - work out fully the function fg(x) or f(g(x)).

    Then compare your equation to the equation given for fg(x) as equal and work out for the missing constant.
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    Or, to put it another way, you have already worked out 2cx + 10 + c...

    Thus,

    2cx + 10 + c = 6x + d

    What must c be if x is not manipulated in any other term?
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    (Original post by ns_2)
    Or, to put it another way, you have already worked out 2cx + 10 + c...

    Thus,

    2cx + 10 + c = 6x + d

    What must c be if x is not manipulated in any other term?
    To be very honest with you, I do not know. I can't think of any method to work that out. Could you cancel out the x's?

    I'm not sure what you mean by x not being manipulated by any other term; I didn't know you could use the word "manipulated" in a mathematical context!

    Thank you for the help thus far.
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    (Original post by anonymous_1947)
    To be very honest with you, I do not know. I can't think of any method to work that out. Could you cancel out the x's?

    I'm not sure what you mean by x not being manipulated by any other term; I didn't know you could use the word "manipulated" in a mathematical context!

    Thank you for the help thus far.
    The only thing/term that has x in your equation is 2cx

    No other bit has x.

    On the provided equation, the only term of x is 6x.

    Hence,

    2cx must equal 6x

    And 10 + c must equal d
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    (Original post by ns_2)
    The only thing/term that has x in your equation is 2cx

    No other bit has x.

    On the provided equation, the only term of x is 6x.

    Hence,

    2cx must equal 6x

    And 10 + c must equal d
    Thank you so much!
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    (Original post by anonymous_1947)
    Thank you so much!
    No problem and good luck
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