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Math Help - factoring quadratic eqations?

  1. #1
    megs94
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    factoring quadratic eqations?

    I'm so confused. How do you do these? I don't understand what to do with the number next to the x2. here's what I did. What am I doing wrong? Please help!
    2x^2+10=9x
    -9x -9x
    2x^2=10-9x=0
    -10 -10
    2x^2-9x=-10
    2 2
    x^2-9x=-5
    (x-10)(x+1)
    x=-10,1
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  2. #2
    Flow Master
    mr fantastic's Avatar
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    Quote Originally Posted by megs94 View Post
    I'm so confused. How do you do these? I don't understand what to do with the number next to the x2. here's what I did. What am I doing wrong? Please help!
    2x^2+10=9x
    -9x -9x
    2x^2=10-9x=0
    -10 -10
    2x^2-9x=-10
    2 2
    x^2-9x=-5
    (x-10)(x+1)
    x=-10,1
    I can't follow your working but I can see at least 1 mistake (you've divided some but not all terms by 2).

    Re-arrange: 2x^2 - 9x + 10 = 0

    Factorise: (2x - 5)(x - 2) = 0.

    Solve: x = 5/2, 2.
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  3. #3
    Newbie
    Joined
    Apr 2008
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    Theres a much easier way to do the factoring part. Cross factoring... if you can get the idea on how to do it, factoring is a breeze Read my post and comment if you'd like Factoring Quadratics for Idiots
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