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Missiles
Missiles asked in Science & MathematicsMathematics · 8 years ago

Algebra - Simplify this expression?

I think I'm making this harder than it needs to be. I just need to simplify it. 7 minus 5 is the numerator and the denominators are 3x+9 minus 4x+12

_7___ - __5__

3x+9 4x+12

Update:

This was actually two seperate fractions:

7__ - _5____

3x+9 4x+12

Sorry that it didn't appear as though it should have...

3 Answers

Relevance
  • ?
    Lv 7
    8 years ago
    Favorite Answer

    7/(3x+9) - 5/(4x+12) =

    7/3(x+3) - 5/4(x+3) =

    (7*4 - 5*3) / 3*4*(x+3) =

    13 / 12(x+3)

  • Como
    Lv 7
    8 years ago

    Presentation dodgy !!!

    7 / (3x + 9) - 5 / (4x + 12)

    7 (4x + 12) - 5 (3x + 9)

    -----------------------------------

    (3x + 9)(4x + 12)

    13x + 84 - 45

    -----------------------

    (3x + 9)(4x + 12)

    13x + 39

    --------------------

    3 (x + 9) 4 (x + 3)

    13 (x + 3)

    ------------------

    12 (x + 9)(x + 3)

    13

    -------------

    12 (x + 9)

  • Dave aka Spider Monkey
    Lv 7
    8 years ago

    7 - 5

    ----------------------------

    3(x+3) 4(x+3) 12(x+3 as lcd

    28 -15

    ---------

    12(x+3) 13/ 12(x+3)

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