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Math Help - Need Help with a few problems.

  1. #1
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    Need Help with a few problems.

    Okay we are doing solving linear equations and I am having trouble on a few:

    * 4(2n-1)=(3n+9)+8

    * x/2 -2=x/5+1

    *-2(t-2)+6t=8t -3

    *7x+5/8=8x-1/8

    Any help would be greatly appreciated.
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  2. #2
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    What rules and techniques are available to you?

    Have you these?

    1) Distributive Proporty of Multiplicatino over Addition
    2) Addition/subtraction
    3) Multiplication/Division
    4) Gather variables to one side and constants to the other

    There may be others. Let's see what you get.
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  3. #3
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    okay for the first one i did this:

    8n-4=3n+9+8
    8n-4=3n+17

    But not how do I get all the n's over to one side??

    Can i do 8n-4=3n+17
    -3n -3n

    Which will leave me with 5n-4=17
    +4+4
    5n=21 divide the 5n but 5 does not go into 21 equally..

    What did I do wrong?
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  4. #4
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    and for the last one I would do this:

    7x+5/8=8-1/8

    I would times everything by 8 to get rid of the fractions and it would come out like this:

    7x+5=8-1

    7x+5=7

    then subbtract the 5 and be left with 7x=2 .... but once again I come up with a fraction.
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  5. #5
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Matt37 View Post
    okay for the first one i did this:

    8n-4=3n+9+8
    8n-4=3n+17

    But not how do I get all the n's over to one side??

    Can i do 8n-4=3n+17
    -3n -3n

    Which will leave me with 5n-4=17
    +4+4
    5n=21 divide the 5n but 5 does not go into 21 equally..

    What did I do wrong?
    Unless you have been told before-hand that the answer is an integer, you have done nothing wrong. Your answer is
    n = \frac{21}{5}

    -Dan
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  6. #6
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Matt37 View Post
    and for the last one I would do this:

    7x+5/8=8-1/8

    I would times everything by 8 to get rid of the fractions and it would come out like this:

    7x+5=8-1

    7x+5=7

    then subbtract the 5 and be left with 7x=2 .... but once again I come up with a fraction.
    Not quite. You started with the right idea but you multiplied by 8 wrong:
    7x + \frac{5}{8} = 8x - \frac{1}{8}

    8 \left ( 7x + \frac{5}{8} \right ) = 8 \left ( 8x - \frac{1}{8} \right )

    56x + 5 = 64x - 1

    Now take it from here.

    -Dan
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  7. #7
    Bar0n janvdl's Avatar
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    Quote Originally Posted by Matt37 View Post

    * x/2 -2=x/5+1
    \frac{x}{2} - 2 = \frac{x}{5} + 1

    10( \frac{x}{2} - 2) = 10( \frac{x}{5} + 1)

    5x - 20 = 2x + 10

    3x = 30

    x = 10

    Quote Originally Posted by Matt37

    *-2(t-2)+6t=8t -3
    -2t + 4 + 6t = 8t - 3

    7 = 4t

    t = \frac{7}{4}

    Quote Originally Posted by Matt37

    *7x+5/8=8x-1/8
    Multiply with 8 straight through

    56x + 5 = 64x - 1

    6 = 8x

    x = \frac{6}{8} = \frac{3}{4}

    Hope it helps
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