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Math Help - Epanding expressions

  1. #1
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    Epanding expressions

    Hi guys any ideas on how I would expand and collect like terms when it comes to these?

    1. (2 + 3x)^3

    2. (6 - 2y)(4x + 1) + 10xy - 2

    Thanks in advance
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  2. #2
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    post your attempt
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  3. #3
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    Quote Originally Posted by komodo View Post
    Hi guys any ideas on how I would expand and collect like terms when it comes to these?

    1. (2 + 3x)^3

    2. (6 - 2y)(4x + 1) + 10xy - 2

    Thanks in advance
    What have you tried? Where are you stuck?

    1. (2 + 3x)(2 + 3x)(2 + 3x) = (Expand first two brackets)(2 + 3x) = .......

    Simple Polynomial Multiplication
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  4. #4
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    I tried to use the FOIL method with no success for the 1st question I got 4+6x+6x+9x^2 after multipliying the first two brackets...am I doing it wrong?

    Thanks
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  5. #5
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    Quote Originally Posted by komodo View Post
    I tried to use the FOIL method with no success for the 1st question I got 4+6x+6x+9x^2 after multipliying the first two brackets...am I doing it wrong?

    Thanks
    No, that's good so far. You can simplify this to 9x^2+12x+4

    So to finish, you need to calculate (9x^2+12x+4)(2+3x). Writing this as:
    2(9x^2+12x+4)+3x(9x^2+12x+4) may help.
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  6. #6
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    Quote Originally Posted by Quacky View Post
    No, that's good so far. You can simplify this to 9x^2+12x+4

    So to finish, you need to calculate (9x^2+12x+4)(2+3x). Writing this as:
    2(9x^2+12x+4)+3x(9x^2+12x+4) may help.
    Thanks mate that gives me 54x^2 + 36x + 27x^3 + 8 .....is this correct?

    For the second question should I FOIL the brackets first then add the other values or is there another method that has to used?

    Thanks
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  7. #7
    Super Member Quacky's Avatar
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    Quote Originally Posted by komodo View Post
    Thanks mate that gives me 54x^2 + 36x + 27x^3 + 8 .....is this correct?

    For the second question should I FOIL the brackets first then add the other values or is there another method that has to used?

    Thanks
    Looks good to me. For the second, just FOIL the brackets first and then collect like terms.

    Edit: My only suggestion is to order your terms, starting with those containing the highest exponent. So write it as 27x^3+54x^2+36x+8
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  8. #8
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    Thanks guys much appreciated
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