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    I am sitting my Standard Grades tomorrow, and have a small query, just to clarify something. Here is
    a question from a past paper:

    18. f(x) = 3? (not to the power n, but x, can't get it to work any other way!!)

    (a) Find f(4) (Okay, done this)

    (b) Given that f(x) = ?27, find x.

    Can anyone help me to solve this?

    Many Thanks!

    [q1]> I am sitting my Standard Grades tomorrow, and have a small query, just to clarify something. Here[/q1]
    [q1]> is a question from a past paper:[/q1]

    [q1]> 18. f(x) = 3? (not to the power n, but x, can't get it to work any[/q1]
    other
    [q1]> way!!)[/q1]

    What do you mean? Where does the question mark come from?

    [q1]> (a) Find f(4) (Okay, done this)[/q1]
    [q1]>[/q1]
    [q1]> (b) Given that f(x) = ?27, find x.[/q1]
    [q1]>[/q1]
    [q1]> Can anyone help me to solve this?[/q1]
    [q1]>[/q1]
    [q1]> Many Thanks![/q1]

    I think that you have neglected to give us the definition of the function
    f(x).

    Regards,

    Richard Hayden.

    ---
    Outgoing mail from Richard Hayden is certified Virus Free. Checked by AVG anti-virus system
    (http://www.grisoft.com). Version: 6.0.317 / Virus Database: 176 - Release Date: 21/01/2002

    "Ally Morrison" <[email protected]> wrote:

    [q1]>I am sitting my Standard Grades tomorrow, and have a small query, just to clarify something. Here[/q1]
    [q1]>is a question from a past paper:[/q1]
    [q1]>[/q1]
    [q1]>18. f(x) = 3? (not to the power n, but x, can't get it to work any other way!!)[/q1]

    That didn't come through very well. Ideally you should render your formulae in ascii.

    I suspect you meant something like f(x) = 3 to the power of x, i.e.
    f(x) = 3^x, is that right?

    [q1]>[/q1]
    [q1]>(a) Find f(4) (Okay, done this)[/q1]

    f(4) = 3^4 = 81
    [q1]>[/q1]
    [q1]>(b) Given that f(x) = ?27, find x.[/q1]

    That would be f(x) = 27, i.e. 3 to the power of x = 27. what is x?

    The general method to solve this kind of question is to take logs:

    log (3^x) = log (27)

    but log (3^x) = x * log (3)

    so x * log(3) = log(27), and x = log(27) / log(3) = 3

    Gareth
 
 
 
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