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Math Help - is this right...?

  1. #1
    Junior Member alwaysalillost's Avatar
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    Post is this right...?

    1/3x = 1/2x - 5
    5 = 1/6x
    x = 30

    Is this right? If it is, how can I check it to show that it's right? Please help. Thnx so much!
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by alwaysalillost View Post
    1/3x = 1/2x - 5
    5 = 1/6x
    x = 30

    Is this right? If it is, how can I check it to show that it's right? Please help. Thnx so much!
    is it 1/2x - 5 or 1/(2x - 5)?

    you can check by pluging in your answer into the original equation and see if everything checks out. you got x = 30, so

    1/3(30) should be equal to 1/2(30) - 5

    not true, your answer would be wrong either way, whether it is 1/2x - 5 or 1/(2x - 5)
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  3. #3
    Junior Member alwaysalillost's Avatar
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    Hmm...well the problem is:

    One-third of a number is 5 less than half of the same number. What is the number?

    and I had posted this before and someone gave me the answer of:

    1/3x = 1/2x - 5
    5 = 1/6x
    x = 30

    but when I went to check it I couldn't get it to make sence. I'm stuck. Can you please help me?! Thanks in advance!
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by alwaysalillost View Post
    Hmm...well the problem is:

    One-third of a number is 5 less than half of the same number. What is the number?

    and I had posted this before and someone gave me the answer of:

    1/3x = 1/2x - 5
    5 = 1/6x
    x = 30

    but when I went to check it I couldn't get it to make sence. I'm stuck. Can you please help me?! Thanks in advance!
    well, you set up the equation correctly, so good job there

    now to solve this thing

    (1/3)x = (1/2)x - 5 ..........we want x on one side
    => (1/3)x - (1/2)x = -5 ....subtracted (1/2)x from both sides
    => (1/3 - 1/2)x = -5
    => (-1/6)x = -5
    => x = 30 ......................multiplied both sides by -6

    Ah, so you were correct!!! I misinterpreted what you wrote due to your lack of parenthesis. i thought you meant to write either 1/2x - 5 or 1/(2x - 5) not (1/2)x - 5 ...........do you see the difference between the three?

    You were not confident in your answer, why? we can check it. plug in x = 30 in both sides and see if they end up the same:

    (1/3)(30) = 10 .......................this is what the left side gives

    (1/2)(30) - 5 = 15 - 5 = 10 ......this is what the right side gives

    so you see, they are equal, you did good
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