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Math Help - Simple algebra I have forgotten how to do

  1. #1
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    Simple algebra I have forgotten how to do

    How do I get from 6x 2(7y 3x) to 12x - 14y?

    I don't understand what I need to do with the numbers outside the brackets in relation to the numbers inside.

    Thanks for le help
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  2. #2
    Super Member Quacky's Avatar
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    Re: Simple algebra I have forgotten how to do

    -2(7y-3x)
    =(-2)\times{7y}+(-2)\times{-3x}

    Can you take it from there?
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  3. #3
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    Re: Simple algebra I have forgotten how to do

    Hi Quacky,

    No I can't. I either go -2(7y-3x) = 14y+6x and then go 6x(-14y+6x) and multiply that out which is wrong. Or I take the 6x(7y-3x) = 42xy-18x^2 which is wrong again when combined with 14y+6x. So I have no idea lol. Any further help would be great
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  4. #4
    Super Member Quacky's Avatar
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    Re: Simple algebra I have forgotten how to do

    Quote Originally Posted by Quacky View Post
    -2(7y-3x)
    =(-2)\times{7y}+(-2)\times{-3x}

    Can you take it from there?
    Quote Originally Posted by JonathonDimblebee View Post
    Hi Quacky,

    No I can't. I either go -2(7y-3x) = 14y+6x and then go 6x(-14y+6x) and multiply that out which is wrong. Or I take the 6x(7y-3x) = 42xy-18x^2 which is wrong again when combined with 14y+6x. So I have no idea lol. Any further help would be great
    Starting where I left off:

    -2(7y-3x)

    =(-2)\times{7y}+(-2)\times{-3x}

    =-14y+6x

    The full expression you have been asked to simplify is 6x-2(7y-3x).

    And we know that -2(7y-3x)=-14y+6x, so the problem becomes:

    6x-14y+6x
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  5. #5
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    Re: Simple algebra I have forgotten how to do

    Wow that's simple. I wouldn't have came up with that in 1,000,000 years. Thanks for your time.
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  6. #6
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    Re: Simple algebra I have forgotten how to do

    Quote Originally Posted by JonathonDimblebee View Post
    How do I get from 6x 2(7y 3x) to 12x - 14y?

    I don't understand what I need to do with the numbers outside the brackets in relation to the numbers inside.

    Thanks for le help
    I suppose the confusing part is in the understanding that 6x is not part of - 2?

    So -2(7y) = -14y and -2(-3x) = 6x, therefore;

    6x - 14y + 6x
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