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Math Help - equation

  1. #1
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    equation

    I haven't done math in years, I have no idea what I'm doing wrong

    this is one of many problems I'm stuck on:

    -6 (x +1) + 4 = 16

    I disribute the negative 6 to the ()

    -6 (-11x) = 66x

    66x=12

    x= 12/66

    Then I don't do that I get:

    -6(2x)+4-4=16-4
    -12x=12
    x=-1

    I've been stuck on this one for hours, I went through the tutorials and everything and I still do not understand.
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  2. #2
    MHF Contributor Mathstud28's Avatar
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    Quote Originally Posted by mdudley View Post
    I haven't done math in years, I have no idea what I'm doing wrong

    this is one of many problems I'm stuck on:

    -6 (x +1) + 4 = 16

    I disribute the negative 6 to the ()

    -6 (-11x) = 66x

    66x=12

    x= 12/66

    Then I don't do that I get:

    -6(2x)+4-4=16-4
    -12x=12
    x=-1

    I've been stuck on this one for hours, I went through the tutorials and everything and I still do not understand.
    Hello
    -6(x+1)+4=16

    First let us distribute that -6 through to get

    -6x-6+4=16

    now combining the second and third term we get

    -6x-2=16

    adding two to each side we get

    -6x=18

    dividing by six we get

    x=-3
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  3. #3
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    Quote Originally Posted by Mathstud28 View Post
    Hello
    -6(x+1)+4=16

    First let us distribute that -6 through to get

    -6x-6+4=16

    now combining the second and third term we get

    -6x-2=16

    adding two to each side we get

    -6x=18

    dividing by six we get

    x=-3
    Ok so I take the -6 and distribute to the ()

    and get -6x-6+4=16

    is that because of the (x+1) = 1x and 1x multiplied by -6 equals -6x?

    then
    -6x-6+4=16
    -6x-2 + 2 = 16 + 2
    -6x = 18
    -6x divided by -6 is x and 18 divided by -6 is negative 3
    x=-3

    so I didn't need to multiply at all? when will I know when to mulitply?
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  4. #4
    Super Member Aryth's Avatar
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    Quote Originally Posted by mdudley View Post
    Ok so I take the -6 and distribute to the ()

    and get -6x-6+4=16

    is that because of the (x+1) = 1x and 1x multiplied by -6 equals -6x?

    then
    -6x-6+4=16
    -6x-2 + 2 = 16 + 2
    -6x = 18
    -6x divided by -6 is x and 18 divided by -6 is negative 3
    x=-3

    so I didn't need to multiply at all? when will I know when to mulitply?
    Not quite:

    (x + 1) includes TWO terms, and when you distribute anything to something with more than one term you distribute it to all terms, for example, say we wanted to distribute the number 2 to the (x + 1):

    2(x + 1)

    What it means to distribute is to multiply each term in the parentheses by what's on the outside:

    2(x) + 2(1)

    Now we multiply:

    2x + 2

    Using this, you can see why:

    -6(x + 1) = -6(x) + -6(1) = -6x - 6

    There you are.
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