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Math Help - need help

  1. #1
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    need help

    2A/3=8+4A

    my problem is to figure out what A is alone but my answer doesnt match the book, i know its either A=12/5 or A=-2.4 but my answer doesnt come close.

    first i tried it 2A/3=8+4A then take 4A from both sides to get -2A/3=8, times by 3 to get rid of it. -2A=24, then devide by -2, A= -12.

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  2. #2
    Moo
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    Hello,

    Your mistake is here :
    then take 4A from both sides to get -2A/3=8
    If you take 4A from both sides, it's :

    8=(2A/3)-4A

    But to substract two elements, they gotta have the same denominator. So write 4A=12A/3 and then do the substraction.
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  3. #3
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    Quote Originally Posted by Moo View Post
    Hello,

    Your mistake is here :

    If you take 4A from both sides, it's :

    8=(2A/3)-4A

    But to substract two elements, they gotta have the same denominator. So write 4A=12A/3 and then do the substraction.
    sorry i dont understand exactly why you increased the 2A to 12A, am i suppose to look at 2A/3 as a fraction?

    It would be a really big help if you could explain alittle step by step, i havent done this type of math for a awhile and trying to get a jump on it again so.. kind tell me in the most simple way please
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  4. #4
    Moo
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    Quote Originally Posted by Jgleer View Post
    sorry i dont understand exactly why you increased the 2A to 12A, am i suppose to look at 2A/3 as a fraction?

    It would be a really big help if you could explain alittle step by step, i havent done this type of math for a awhile and trying to get a jump on it again so.. kind tell me in the most simple way please
    I'll try

    2A/3=8+4A.

    --------------------
    What you did :
    (2A/3)-4A=-2A/3

    Remember the rules of operations (pemdos or bodmas), the division comes before the substraction !

    What you did here is first substract 4A to 2A and then divide by 3. This is false.

    2A/3 - 4A = 8

    Multiply both sides by 3 in order to get rid of the division.

    --> 2A - 12A=24

    and now you can solve
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  5. #5
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    Quote Originally Posted by Moo View Post
    I'll try

    2A/3=8+4A.

    --------------------
    What you did :
    (2A/3)-4A=-2A/3

    Remember the rules of operations (pemdos or bodmas), the division comes before the substraction !

    What you did here is first substract 4A to 2A and then divide by 3. This is false.

    2A/3 - 4A = 8

    Multiply both sides by 3 in order to get rid of the division.

    --> 2A - 12A=24

    and now you can solve
    Thank you so much Moo!, that made alot more sense. When i would multiply by 3 i just did it to 8 and not to 4A. I understand taking 2A/3=8+4A Then getting to 2A=24+12A now. after that i would substract 12 and get -10A/24 = -2.4.

    Thanks again Moooo
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