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Math Help - Need help finding a formula from graph

  1. #1
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    Exclamation Need help finding a formula from graph




    How would we find the formula for problem 28b? I think the vertical asymptote is 3. And that I think the formula is in the format 1/x^2 but don't know how to get the formula. Please help me with this. Thank you so much!
    Last edited by florx; May 4th 2010 at 10:22 PM.
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  2. #2
    MHF Contributor ebaines's Avatar
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    To find a possible function, consider that this function becoms undefined at x = 3, similar to how the graph 1/x^2 becomes undefines at x = 0. So your first guess might be the function is 1/x^2 shifted to the right by 3. Recall that the graph of a function function f(x-a) is the same as f(x) but shifed a units to the right. So to shift 1/x^2 by 3 units to the right you have to change the x to x-3:

    y = 1/(x-3)^2.

    But if you do the math you'll see that this is consistently too low by one. So you need to add one to the equation:

    y = 1/(x-3)^2 + 1.
    Last edited by ebaines; May 6th 2010 at 05:29 AM.
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  3. #3
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    Great explanation! Thank you so much.
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  4. #4
    Member grgrsanjay's Avatar
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    Quote Originally Posted by ebaines View Post
    To find a possible function, consider that this function becoms undefined at x = 3, similar to how the graph 1/x^2 becomes undefines at x = 0. So your first guess might be the function is 1/x^2 shifted to the right by 3. Recall that the graph of a function function f(x-a) is the same as f(x) but shifed a units to the right. So to shift 1/x^2 by 3 units to the right you have to change the x to x-3:

    y = 1/(x-3)^2.

    But if you do the math you'll see that this is consistently too low by one. So you need to add one to the equation:

    y = 1/(x-3)^2 + 1.
    brilliant idea !!,
    thanks
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