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Math Help - Square root

  1. #1
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    Square root

    Solve this equation when y=0

    y=\sqrt{4-x^2}
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by bret80
    Solve this equation when y=0

    y=\sqrt{4-x^2}
    First of all, to do LaTeX, you need to put your expression between [ math ] and [ /math ] . (Without the spaces!)

    0 = \sqrt{4-x^2}. Square both sides:

    0 = 4 - x^2

    x^2 = 4

    x = \pm 2

    Whenever you square both sides of an equation ALWAYS check to make sure that your solution set satisfies your original equation as squaring occasionally adds extra solutions. In this case, both solutions work.

    -Dan
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    Quote Originally Posted by topsquark
    Whenever you square both sides of an equation ALWAYS check to make sure that your solution set satisfies your original equation as squaring occasionally adds extra solutions.
    Not neccesarily. If all of your steps are equivalent to each other (if and only if; you might have seen me do that a number of times) then no check is required.
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  4. #4
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by ThePerfectHacker
    Not neccesarily. If all of your steps are equivalent to each other (if and only if; you might have seen me do that a number of times) then no check is required.
    Well, it's a good idea for us "lesser mortals" anyway. We can't ALL be "perfect."

    -Dan
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