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Thread: [SOLVED] Factor 4x^2+31x-8

  1. #1
    calligrapher
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    [SOLVED] Factor 4x^2+31x-8

    How do you factor 4x^2+31x-8?

    Thanks in advance,

    ~calligrapher~
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  2. #2
    Super Member angel.white's Avatar
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    Quote Originally Posted by calligrapher View Post
    How do you factor 4x^2+31x-8?

    Thanks in advance,

    ~calligrapher~
    $\displaystyle (4x-1)(x+8)$
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  3. #3
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    Here's a good method for solving quadratics like these when $\displaystyle a > 1$

    Multiply a and c and find the factors of there product whose sum is b. In this case $\displaystyle 4 \cdot -8 = -32$ and $\displaystyle 32 = 32 \cdot -1$ and $\displaystyle 32 + (-1) = 31$ These are what numbers you try to get when you foil.

    So it will factor to
    $\displaystyle (4x - 1)(x + 8)$

    and $\displaystyle x \in \{\frac{1}{4}, -8\}$
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  4. #4
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by SnipedYou View Post
    Here's a good method for solving quadratics like these when $\displaystyle a > 1$

    Multiply a and c and find the factors of there product whose sum is b. In this case $\displaystyle 4 \cdot -8 = -32$ and $\displaystyle 32 = 32 \cdot -1$ and $\displaystyle 32 + (-1) = 31$ These are what numbers you try to get when you foil.

    So it will factor to
    $\displaystyle (4x - 1)(x + 8)$

    and $\displaystyle x \in \{\frac{1}{4}, -8\}$
    How can it have a solution when it isn't an equation?

    -Dan
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