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Math Help - simple algebra problem please help

  1. #1
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    simple algebra problem please help

    5x+10x=15/1
    5x+10=15/(1 x x)
    5+10=15/(1 x x x x)

    Can someone tell me what I am doing wrong?
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  2. #2
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    Quote Originally Posted by Ry122 View Post
    5x+10x=15/1
    5x+10=15/(1 x x)
    5+10=15/(1 x x x x)

    Can someone tell me what I am doing wrong?
    Is 5x+10x=15/1 meant to be 5x^2 + 10x^2 = \frac{15}{1} ?
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  3. #3
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    yes
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  4. #4
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    Quote Originally Posted by Ry122 View Post
    yes
    Then the next line would clearly be 15x^2 = 15 ......
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  5. #5
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    what do u mean?
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  6. #6
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    im not trying to solve for x. just tell me if this is right, and if it isnt please correct me.
    5x+10x=15/1
    5x+10=15/(1 x x)
    5+10=15/(1 x x x x)
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  7. #7
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    Quote Originally Posted by Ry122 View Post
    im not trying to solve for x. just tell me if this is right, and if it isnt please correct me.
    5x+10x=15/1
    5x+10=15/(1 x x)
    5+10=15/(1 x x x x)
    I have no idea what you're trying to if you're not solving for x. What you have posted makes no mathematical sense from the second line onwards.
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  8. #8
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    Simplification

    Primarily, you can add 5x^2 and 10x^2 getting 15x^2. You can then divide the whole equation with 15, getting equation

    1=x^2 (1)

    Thus x is square root of 1, which can be either +1 or -1.

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  9. #9
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    im not trying to solve for x. just tell me if this is right, and if it isnt please correct me.
    5x+10x=15/1

    5x+10=15/(1 x x) WRONG, please tell me the reasons for your answer

    5+10=15/(1 x x x x) WRONG again, please tell me the reasons for your answer
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  10. #10
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    5x+10x=15/1

    WRONG:
    5x+10=15/(1 x x)

    this is the right thing to do:
    ax+bx=(a+b)x -> you get 15x=15 now divide with with 15 and you are done.

    Why are these two steps wrong:
    WRONG:
    5x+10=15/(1 x x) & 5+10=15/(1 x x x x)

    You are obviously dividing with x . When dividing the equation you must be sure to divide both sides! So in your case you have divided 15 with x, that is OK. On the left side you have divided ONLY 10 with x and forgot the 5.
    The right thing would be:

    5+10=15/(1 x x) Or long way: 5x+10x=15 /x -> 5x/x+10x/x=15/x
    5+10=15/x
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