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Math Help - domain

  1. #1
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    domain

    Can anyone help me solve this I cant figure out domain and range no matter how much I study it.
    Let f(x)=(x^2+14x+49)/(x+7) or x squared plus 14x plus 49 all over x plus 7
    Find the domain.
    I want to say that the domain has to be x > or = to -7 (x is greater than or equal to -7).
    Thanks
    AC
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  2. #2
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    for your rational function, the domain is all real numbers except x = -7

    domain is the values of x you can use without breaking any rules.

    at your level of study, the rules are ...

    no division by 0

    no square root, fourth root, sixth root, etc. of negative values

    no logs of non-positive values.
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  3. #3
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    I still cant get the correct domain

    So if i put the domain in interval notation would it be [-7, Inf) It looks on the graph like that would work but when i enter it in to my online homework it says its wrong. I still dont get what i am doing wrong
    Amanda
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  4. #4
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    no ... only x = -7 is excluded. your notation [-7, \infty) is the set of all reals greater than -7 and including -7.

    here is the domain ...

     (-\infty, -7) \cup (-7, \infty)

    or

    {x \in \Re, \, x \neq -7}
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