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Math Help - Find the domain

  1. #1
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    Find the domain

    Find the domain of
     log_e (x + \sqrt {x^2 +1})

    I think there is some trick to it
    I had all real x values
    but it seems too easy for a 2 mark question

    any thoughts?

    Thanks
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  2. #2
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    Quote Originally Posted by differentiate View Post
    Find the domain of
     log_e (x + \sqrt {x^2 +1})

    I think there is some trick to it
    I had all real x values
    but it seems too easy for a 2 mark question

    any thoughts?

    Thanks
    That's exactly right. x^2> 0 for all x so x^2+ 1> 1 and \sqrt{x^2+ 1}>\sqrt{x^2}> |x|. For all x, x+ \sqrt{x^2+ 1}> 0 so the domain is all real numbers.
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