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Math Help - Substituting numbers for variables

  1. #1
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    Substituting numbers for variables

    Say I want to test x=-2 in the equation -3x^2+3. When I replace x with -2, do I put parenthesis around it? My calculator gives me two different answers for (-2)^2 and -2^2.
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  2. #2
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    Re: Substituting numbers for variables

    Quote Originally Posted by shane805 View Post
    Say I want to test x=-2 in the equation -3x^2+3. When I replace x with -2, do I put parenthesis around it? My calculator gives me two different answers for (-2)^2 and -2^2.
    $(-2)^2$ means the square of negative two: $(-2)(-2)=4$.

    $-2^2$ means the negative of two squared: $-(2)(2)=-4$.
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    Re: Substituting numbers for variables

    Yeah I totally understand that the two are different, just wondering which one to use when solving for x. Say I have -3x^2+3, and I'm solving for x=-2, do I end up with -3(-2)^2 or -3*-2^2? something tells me it's the first of the two..
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    Re: Substituting numbers for variables

    Quote Originally Posted by shane805 View Post
    Yeah I totally understand that the two are different, just wondering which one to use when solving for x. Say I have -3x^2+3, and I'm solving for x=-2, do I end up with -3(-2)^2 or -3*-2^2? something tells me it's the first of the two..
    That is correct.
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