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Math Help - factoring

  1. #1
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    factoring

    a. f(x) = x2-5x-14 b. f(x) = 9x2 -4
    c. f(x) = 6x2 -x -12



    factor the following
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  2. #2
    Senior Member euclid2's Avatar
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    Quote Originally Posted by william View Post
    a. f(x) = x2-5x-14 b. f(x) = 9x2 -4
    c. f(x) = 6x2 -x -12



    factor the following
    You should know how to factor.
    a)
     f(x)= x^2 - 5x - 14
     f(x)= (x+7)(x-2)
    Find the two numbers that multiply to make -14 and add to get -5.
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  3. #3
    Senior Member euclid2's Avatar
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    Quote Originally Posted by william View Post
    a. f(x) = x2-5x-14 b. f(x) = 9x2 -4
    c. f(x) = 6x2 -x -12



    factor the following
    b)
     f(x)= 9x^2 - 4
     f(x)= (3x+2)(3x-2)

    This is known as a difference of squares when factoring. When both numbers can be square root to get an even number, it is a difference of squares, notice how the even square root is in both brackets, with opposite signs distributing to;
     f(x)= 9x^2 - 4
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  4. #4
    Senior Member euclid2's Avatar
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    Quote Originally Posted by william View Post
    a. f(x) = x2-5x-14 b. f(x) = 9x2 -4
    c. f(x) = 6x2 -x -12



    factor the following
    c.

     f(x)= 6x^2 - x - 12
     f(x)= (2x-3)(3x+4)

    Again, simply find the numbers that multiply to -12 and add to -x. Always remember the last sign in the equation, it is very important. If it is negative, the signs will be difference in the set of brackets. If it is positive the signs will be the same, they will both be what the first sign is.
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  5. #5
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    Quote Originally Posted by euclid2 View Post
    You should know how to factor.
    a)
     f(x)= x^2 - 5x - 14
     f(x)= (x{\color{red}+}7)(x{\color{red}-}2)
    Find the two numbers that multiply to make -14 and add to get -5.
    Small mistakes in red. It should be  f(x)= (x{\color{red}-}7)(x{\color{red}+}2) .

    It's always wise to expand your answer as a check.
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  6. #6
    Senior Member euclid2's Avatar
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    Quote Originally Posted by mr fantastic View Post
    Small mistakes in red. It should be  f(x)= (x{\color{red}-}7)(x{\color{red}+}2) .

    It's always wise to expand your answer as a check.
    Absolutely, thanks for pointing that out, I did it quickly, should have checked.
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