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    a) Find the inverse function f^-1(x) of the function f(x)=3^(x-1)
    b)The curve C has the Cartesian equation y=3^(x-1)
    By writing lny in terms of x, find an expression for dy/dx in terms of x.
    I've answered the first part and got an answer of f^-1(x)=((lnx)/(ln3))+1
    so for the second part I've got lny=(x-1)ln3 but I don't know where to go from here. please can someone give me a hint for the next step.

    This is C4

    However, what you need to do, is when you differentiate any value of y, multiply the differentiated y value by Dy/dx.

    e.g. ln(y) differentiated should be 1/y(Dy/Dx)

    After this, you'll have an expression with Dy/Dx, y, and ,. rearrange to make Dy/dx the subject of the equation in terms of y and x.
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    Hope you can read that
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