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C3 transformation of lnx graph help :)

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    Hey i have been doing some revision and forgot how this came about:

    i was trying to draw the graph y=ln(3-x)

    which i know that its a reflection in the y axis due to the -x but doesn't the positive 3 mean a translation in the x axis which means it moves left by 3/ but the example in the book says it moves right by 3?!

    am i missing something here?:confused:

    thanks for help xxx
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    (Original post by DreamsComeTrue.)
    Hey i have been doing some revision and forgot how this came about:

    i was trying to draw the graph y=ln(3-x)

    which i know that its a reflection in the y axis due to the -x but doesn't the positive 3 mean a translation in the x axis which means it moves left by 3/ but the example in the book says it moves right by 3?!

    am i missing something here?:confused:

    thanks for help xxx
    It should be reflected in the y-axis and moved 3 to the left.
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    (Original post by DreamsComeTrue.)
    Am i missing something here?:confused:

    thanks for help xxx
    Yes, you are. The book is correct.

    ln(3-x)

    = ln (-(x-3))

    So you are subtracting 3 from x and the graph is moved to the right.

    See attached.

    edit: You need to consider what has been done to the "x". The fact that there is a minus sign in front, is probably what confused the issue.
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    (Original post by ghostwalker)
    Yes, you are. The book is correct.

    ln(3-x)

    = ln (-(x-3))

    So you are subtracting 3 from x and the graph is moved to the right.

    See attached.

    edit: You need to consider what has been done to the "x". The fact that there is a minus sign in front, is probably what confused the issue.
    your graph cuts the axis at wrong coordinates in your attached image
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    (Original post by rbnphlp)
    your graph cuts the axis at wrong coordinates in your attached image
    How so?

    (Original post by rbnphlp)
    when x=3 , y=0
    Care to check that again.
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    When x is 0, y= ln 3 = 1.098...
    When x = 2, y = 0
    When x = 3 is undefined since as you go up to 3, the graph goes off to "minus infinity".
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    I believe you are Correct.

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Updated: September 5, 2009
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