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    When expanding out a binomial for example: (2-3x)^5 ('^' indicating the indice)

    Will it go to: 2^5 + (5C1)(2^4)(-3x)...

    I get really confused as to if the indices go inside the brackets or outside of the brackets, can someone help please.
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    (Original post by lummzie)
    When expanding out a binomial for example: (2-3x)^5 ('^' indicating the indice)

    Will it go to: 2^5 + (5C1)(2^4)(-3x)...

    I get really confused as to if the indices go inside the brackets or outside of the brackets, can someone help please.
    That's correct. The next term would be (5C2)(2^3)(-3x)^2 and NOT (5C2)(2^3)(-3^2 x) if that's what you're asking. So, really, the indices go outside the bracket, i.e: you raise the entire term to the exponent.
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    (Original post by Zacken)
    That's correct. The next term would be (5C2)(2^3)(-3x)^2 and NOT (5C2)(2^3)(-3^2 x) if that's what you're asking. So, really, the indices go outside the bracket, i.e: you raise the entire term to the exponent.
    Thank you so much, I now realise why I always get binomial wrong a lot its because I put (5C2)(2^3)(-3^2 x) instead of (5C2)(2^3)(-3x)^2. So then will the next be (5C3)(2^2)(-3X)^3 ?
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    (Original post by lummzie)
    Thank you so much, I now realise why I always get binomial wrong a lot its because I put (5C2)(2^3)(-3^2 x) instead of (5C2)(2^3)(-3x)^2. So then will the next be (5C3)(2^2)(-3X)^3 ?
    Correct!
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    (Original post by Zacken)
    Correct!
    So if I expanded (5C2)(2^3)(-3x)^2 would I expand this part (5C2)(2^3)(-3x) first and then square it?
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    (Original post by lummzie)
    So if I expanded (5C2)(2^3)(-3x)^2 would I expand this part (5C2)(2^3)(-3x) first and then square it?
    Nopes, - to clarify, let me introduce more brackets, it should be:

    (5C2) * (2^3) * ((-3x)^2) = (5C2) * (2^3) * ((-3x) * (-3x)) = (5C2) * (2^3) * (9x^)
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    (Original post by Zacken)
    Nopes, - to clarify, let me introduce more brackets, it should be:

    (5C2) * (2^3) * ((-3x)^2) = (5C2) * (2^3) * ((-3x) * (-3x)) = (5C2) * (2^3) * (9x^)
    Okay thank you so much, this makes so much more sense now.
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    (Original post by lummzie)
    Okay thank you so much, this makes so much more sense now.
    You're very welcome. :cool:
 
 
 
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