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Math Help - Algebra and expressions

  1. #1
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    Algebra and expressions

    hello i am not quite sure how to work out these questions could someone please explain to me what to do. Thanxx

    Q1.
    a. simplify 3a(squared)bx8a(cubed)b(squared)
    b. Factorise completely x(squared)+xy-2x-2y

    DOES ANYONE KNOW HOW TO WORK THIS OUT
    Factorise completely x(squared)+xy-2x-2y
    Last edited by sammyfox07; September 30th 2007 at 07:47 AM.
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by sammyfox07 View Post
    hello i am not quite sure how to work out these questions could someone please explain to me what to do. Thanxx

    Q1.
    a. simplify 3a(squared)bx8a(cubed)b(squared)
    b. Factorise completely x(squared)+xy-2x-2y
    3a^2b \cdot 8a^3b^2 = (3 \cdot 8)(a^2 \cdot a^3)(b \cdot b^2) = 24a^5b^3

    Quote Originally Posted by sammyfox07 View Post
    Q2. Factorise this expression into double brackets
    a. x(squared)-2x-120
    x^2 - 2x - 120

    List all the factors of -120:
    1, -120
    2, -60
    3, -40
    4, -30
    5, -24
    6, -20
    10, -12
    etc

    until you get to a pair that adds up to -2, which is the last pair that I listed.

    So:
    x^2 - 2x - 120 = (x + 10)(x - 12)

    -Dan
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