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Math Help - I need a formula for these 2 problems?

  1. #1
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    I need a formula for these 2 problems?

    4x + 9 = 7x

    and

    2r - 6 = 7r +24

    I am very confused. I don't want simply the answer... a formal to solve these problems will do me a lot of good.. I don't want to fail this assignment (I have 33 questions) so I would like a formula to solve these type of questions rather than just the answer. I already know I asked for help on a question, but I really don't understand the formulas for these type of problems.
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  2. #2
    MHF Contributor harish21's Avatar
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    Quote Originally Posted by hoiguy1208 View Post
    4x + 9 = 7x

    and

    2r - 6 = 7r +24

    I am very confused. I don't want simply the answer... a formal to solve these problems will do me a lot of good.. I don't want to fail this assignment (I have 33 questions) so I would like a formula to solve these type of questions rather than just the answer. I already know I asked for help on a question, but I really don't understand the formulas for these type of problems.
    there is no specific formula for questions like these. you have to solve these questions by secluding the variable.

    The first one would be done this way:
    4x + 9 = 7x

    subtract 4x from both sides:

    4x + 9 - 4x = 7x - 4x

    so, 9 = 3x

    now divide both sides by 3, because you have to find out what x is:

    \frac{9}{3} = \frac{3x}{3}

    this gives you:

    3 = x

    So the value of x is 3.

    Can you try doing the same for your second problem. Give it a shot and reply back if you have problems!
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  3. #3
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    Attempt at a few, can someone check these?

    6a = 26 +4a

    6a -4a = 26 -4a

    2a = 26

    Divide both by 2

    a= 13?


    here is my worst attempt at 4 numbers, which I kinda of suck at.

    6x + 7 = 8x-13

    6x +7 -6x = 8x-13-6x

    7=2x-13

    As far as I got on 4 numbers.


    Can someone tell me if I got the first one correct and try to guide me through the 4 number ones?
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  4. #4
    Senior Member Stroodle's Avatar
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    Quote Originally Posted by hoiguy1208 View Post
    6a = 26 +4a

    6a -4a = 26 -4a

    2a = 26

    Divide both by 2

    a= 13?


    here is my worst attempt at 4 numbers, which I kinda of suck at.

    6x + 7 = 8x-13

    6x +7 -6x = 8x-13-6x

    7=2x-13

    As far as I got on 4 numbers.


    Can someone tell me if I got the first one correct and try to guide me through the 4 number ones?
    Both are correct.

    For the second one, you can then add 13 to both sides, then divide both sides by 2, giving x=10.
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  5. #5
    MHF Contributor harish21's Avatar
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    Quote Originally Posted by hoiguy1208 View Post
    6a = 26 +4a

    6a -4a = 26 -4a

    2a = 26

    Divide both by 2

    a= 13?


    here is my worst attempt at 4 numbers, which I kinda of suck at.

    6x + 7 = 8x-13

    6x +7 -6x = 8x-13-6x

    7=2x-13

    As far as I got on 4 numbers.


    Can someone tell me if I got the first one correct and try to guide me through the 4 number ones?
    6a -4a = 26 -4a

    2a = 26

    Divide both by 2

    a= 13

    This is correct.

    2.
    Do not call it your worst attempt. What you have done is actually the correct way of approaching to the solution. for the second problem, you have reached :

    7=2x-13

    so,

    7+13 = 2x -13+13

    20 = 2x

    divide by 2,

    x=10

    Practice a few more, and you'll nail these kind of problems!
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  6. #6
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    Another few attempts

    Deleted, accidental clicked "post too fast" 2 times. Double post - reason for deleting.
    Last edited by hoiguy1208; March 30th 2010 at 08:40 PM.
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  7. #7
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    Another few attempts

    Thank you for all your help. I am grateful. Here is another few attempts if you all want to over look them:

    #1

    N-14=3N
    N-14-1n=3N-1N
    14=2n
    Divide both by 2, N=7

    #2

    10y-13=5y+7
    10y-13+13=5y+7+13

    10y=5y+20
    10y-10y=5y+20-10y

    5y=10

    divide both by 5... y =2?

    #3
    3y+17=5y
    3y+16-3y=5y-3y
    16=2y

    Divide both by 2 y =8?
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