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Math Help - How do I simplify this type of expression?

  1. #1
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    How do I simplify this type of expression?

    I need help simplifying an expression that is in this form:

    (3x + 12) / (9x^2 - 144)

    thanks in advanced.
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  2. #2
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by jenbones View Post
    I need help simplifying an expression that is in this form:

    (3x + 12) / (9x^2 - 144)

    thanks in advanced.
    Hint: 9x^2-144= (3x)^2-(12)^2

    Do you know how to factor this?
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  3. #3
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    No, I am not very good at factoring.
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  4. #4
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by jenbones View Post
    No, I am not very good at factoring.
    Remember the difference of squares formula? a^2-b^2=(a+b)(a-b)
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  5. #5
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    yes, I remember that formula.
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  6. #6
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    Quote Originally Posted by jenbones View Post
    yes, I remember that formula.
    Utilising it will allow you to simplify by cancelling the numerator with one of the factors.
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  7. #7
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    Quote Originally Posted by jenbones View Post
    I need help simplifying an expression that is in this form:

    (3x + 12) / (9x^2 - 144)

    thanks in advanced.

    \frac{3x + 12}{9x^2 - 144} = \frac{3x + 12}{(3x+12)(3x-12)} = \frac{1}{3x-12}
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  8. #8
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    Quote Originally Posted by yehoram View Post
    \frac{3x + 12}{9x^2 - 144} = \frac{3x + 12}{(3x+12)(3x-12)} = \frac{1}{3x-12}
    isn't the answer (1) / (3 (x - 4)) ??
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  9. #9
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    Quote Originally Posted by jenbones View Post
    isn't the answer (1) / (3 (x - 4)) ??
    Yes...

    \displaystyle\frac{1}{3x-12}=\frac{1}{3(x)-3(4)}=\frac{1}{3(x)+3(-4)}=\frac{1}{3(x-4)}
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