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Math Help - Factorise

  1. #1
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    Smile Factorise

    -3(5x - 8)^2 + 27
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  2. #2
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    -3(5x - 8)^2 + 27
    Foil it first
     -3[25x^2-80x+64]+27
    Distribute the -3
     -75x^2+240x-192+27
     -75x^2+240x-165
    Factor out a -15
    -15[5x^2-16x+11]
    factor
    -15(x-1)(5x-11)
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  3. #3
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    Quote Originally Posted by Joker37 View Post
    -3(5x - 8)^2 + 27
    Easier to take out -3 as a common factor and then DOTS.

    -3(5x - 8)^2 + 27 = -3[(5x - 8)^2 - 9]

     = -3[(5x - 8)^2 - 3^2]

     = -3[(5x - 8 + 3)(5x - 8 - 3)]

     = -3(5x - 5)(5x - 11)

     = -15(x-1)(5x-11).
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