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Math Help - Quickie about completing the square

  1. #1
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    Quickie about completing the square

    Hi, having troubles once again, not a foggy what i'm doing wrong

    question is

    'by completing the square, solve the quadratic equation, giving your answer in surd form'

    sorry i don't know how to put in that math notation stuff.

    : xsquared + 3x - 5 = 0

    this is where i got

    (x + 3/2)squared - 29/4 = 0
    x = -3/2 +or- squarerootof 29/4

    whereas they get

    x = -3/2 +or- squarerootof 29/2

    other questions where i was expecting the last bit (the squareroot-of-bit) to be Something/4, the book was saying Something/2. i just dont see how they got there. please help
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  2. #2
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    e^(i*pi)'s Avatar
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    West Midlands, England
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    Quote Originally Posted by artem1s View Post
    Hi, having troubles once again, not a foggy what i'm doing wrong

    question is

    'by completing the square, solve the quadratic equation, giving your answer in surd form'

    sorry i don't know how to put in that math notation stuff.

    : xsquared + 3x - 5 = 0

    this is where i got

    (x + 3/2)squared - 29/4 = 0
    x = -3/2 +or- squarerootof 29/4

    whereas they get

    x = -3/2 +or- squarerootof 29/2

    other questions where i was expecting the last bit (the squareroot-of-bit) to be Something/4, the book was saying Something/2. i just dont see how they got there. please help
    This is because the square root of 4 is 2:

    \sqrt({\frac{29}{4}}) = \frac{\sqrt(29)}{2}
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  3. #3
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    aRRCHHHALMFLAKSM

    such a schoolboy error, mega embarrassed now. thanks !!!!!!!!
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