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Math Help - rational expressions

  1. #1
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    rational expressions

    f(x) =square root of x - 1/x + 2
    Determine values of x for which
    1) f(x)= 0
    2) f(x) will be a real number.
    Thanks in advance
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  2. #2
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    Re: rational expressions

    Quote Originally Posted by Bonganitedd View Post
    f(x) =square root of x - 1/x + 2
    Determine values of x for which
    1) f(x)= 0
    2) f(x) will be a real number.
    You must learn to post readable questions.

    Is it it \sqrt{\frac{x-1}{x+2}}\text{ or }\frac{\sqrt{x-1}}{x+2} or something else altogether?

    Learn to use grouping symbols.
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  3. #3
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    Re: rational expressions

    The first one.
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  4. #4
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    Re: rational expressions

    Quote Originally Posted by Bonganitedd View Post
    The first one.
    In that case you should have posted "f(x) =square root{(x - 1)/(x + 2)}"
    See the grouping?

    Solve \frac{x-1}{x+2}\ge 0.
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  5. #5
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    Re: rational expressions

    X>=1 nt sure abt the denomenator
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  6. #6
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    Re: rational expressions

    Do you know "if a> b and c is positive then ac> bc. If a> b and c is negative then ac< bc."

    If x+ 2 is positive, then multiplying both sides by it gives x- 1\ge 0. When is x+ 2 positive?

    If x+2 is negative, then multiplying both sides by it gives x- 1\le 0. When is x+ 2 negative?
    Thanks from Bonganitedd
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  7. #7
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    Re: rational expressions

    rational expressions-untitled2.gif
    Thanks from Bonganitedd
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  8. #8
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    Re: rational expressions

    Thanks you all who contributed.
    I now understand the problem
    1) The expression will be equal to zero if we set the radicand numerator = 0
    2)f(x) will be real 1) x is nt = -2
    X>=1 or x< -2
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  9. #9
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    Re: rational expressions

    Do you now understand that this was NOT a "rational expression"?
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