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    • Thread Starter
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    Hi guys,

    I need help to factorise this very easy expression:

    x^2-4


    Thanks
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    (Original post by Sophie Maywood)
    Hi guys,

    I need help to factorise this very easy expression:

    x^2-4


    Thanks
    complete the square!

    (x-2)(x+2)

    edit: difference of two squares...my mistake.
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    x^2 is x squared.

    4 is a square number.

    The subtraction means "difference".

    Put this together and what do you realise?
    • Thread Starter
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    Ah, so it's a difference of 2 squares, which means the coefficient of x cancel each other out, yes?
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    Wiki Support Team
    (Original post by Sophie Maywood)
    Ah, so it's a difference of 2 squares, which means the coefficient of x cancel each other out, yes?
    That's right. Expanding out (x-2)(x+2) will give you a +2x term and a -2x term.
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    Ok thanks !
 
 
 
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