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Math Help - How do you solve a quadratic equation by completing the square if the x coeff is odd

  1. #1
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    How do you solve a quadratic equation by completing the square if the x coeff is odd

    Hi guys basically I'm trying to solve the following equation by completing the square...

    x2-3x-5=0

    However, when I try and form the square and complete it I seem to run into trouble

    (x-1.5)(x-1.5)=x2-3x+2.25

    (x-1.5)2-7.25=0

    (x-1.5)2=7.25

    x-1.5= (root 29) divided by 2

    Then I get kinda stuck. Is this right so far? Can someone please guide me through what to do? Thanks very much for any help.
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  2. #2
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    Re: How do you solve a quadratic equation by completing the square if the x coeff is

    Quote Originally Posted by MattA147 View Post
    Hi guys basically I'm trying to solve the following equation by completing the square...

    x2-3x-5=0

    However, when I try and form the square and complete it I seem to run into trouble

    (x-1.5)(x-1.5)=x2-3x+2.25

    (x-1.5)2-7.25=0

    (x-1.5)2=7.25

    x-1.5= (root 29) divided by 2

    Then I get kinda stuck. Is this right so far? Can someone please guide me through what to do? Thanks very much for any help.

    (x-1.5)^2 =7.25
    x-1.5 = rad 7.25
    x=4.19
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  3. #3
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    Re: How do you solve a quadratic equation by completing the square if the x coeff is

    Quote Originally Posted by MattA147 View Post
    Hi guys basically I'm trying to solve the following equation by completing the square...
    x2-3x-5=0
    \\x^2-3x-5=0\\x^2-3x+(1.5)^2=5+(1.5)^2\\(x-1.5)^2=7.25

    x=1.5\pm\sqrt{7.25}
    Thanks from bjhopper
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