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Math Help - Graphing y=-ln|x+2| +3.

  1. #1
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    Graphing y=-ln|x+2| +3.

    I'm having problems with this maths question:

    Graph y=-ln|x+2| +3.


    I don't understand why even tho +3 is at the back, the graph moved down 3 units instead of up? Does reflection in x-axis come AFTER translations?
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  2. #2
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    Quote Originally Posted by Lushorama View Post
    I'm having problems with this maths question:

    Graph y=-ln|x+2| +3.


    I don't understand why even tho +3 is at the back, the graph moved down 3 units instead of up? Does reflection in x-axis come AFTER translations?
    y = -(ln|x + 2| - 3). Therefore do the translations and then reflect.

    Alternatively, ln|x| --> ln|x + 2| --> -ln|x + 2| --> -ln|x + 2| + 3.

    There's more than one set of ordered transformations that will achieve the same outcome ....
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  3. #3
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    However, whether you do it as y= -(ln|x+2|- 3) or y= -ln|x+2|+ 3, the graph is 3 places higher than the graph of y= -3ln|x+2|, not lower!

    For example, for x= -1, ln|-1+2|= ln|1|= 0 so y= -(0- 3)= 3 while -ln|x+2|+ 3= -ln|1|+ 3= 3. The graph y= -ln(x+2) passes through the point (-1, 0) while the graph of y= -ln|x+2|+ 3 passes through the point (-1, 3), three places higher.

    If your problem is actually y= -(ln|x+2|+ 3)= -ln|x+2|- 3, then the graph passes through (-1, -3), three places lower.
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