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Math Help - [SOLVED] X=1 Solve

  1. #1
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    [SOLVED] X=1 Solve

    My teach said there was a common factor to factor out before i can substitute the value of 1 in for x, but i have no clue how to find it..

    (3-x)/(3x^2-9x)

    if i put zero in on the bottom it becomes 0 and i can't divide by zero, someone please show me their solutions, don't skip any steps please (and if u could, explain some of the steps that would be great)
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  2. #2
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    (3-x)
    ________
    (3x^2-9x)

    Now, we see that both 3x^2 and 9x are divisible by 3 (3x3, 3x1) and they also share x (x^2 = x*x). So we can change that into:

    (3-x)
    ________
    3x(x-3)

    Here, we notice that (3-x) = -(x-3), so

    -(x-3)
    ______
    3x(x-3)

    Divide both sides of the fraction by (x-3):

    -1
    ___
    3x

    Now, input x=1 here to get -1/3

    Note that if you want to graph this, the original domain still applies.
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  3. #3
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    Quote Originally Posted by Noxide View Post
    My teach said there was a common factor to factor out before i can substitute the value of 1 in for x, but i have no clue how to find it..

    (3-x)/(3x^2-9x)

    if i put zero in on the bottom it becomes 0 and i can't divide by zero, someone please show me their solutions, don't skip any steps please (and if u could, explain some of the steps that would be great)
    do you mean substitute 3 for x ?

    \frac{3-x}{3x^2 - 9x} = \frac{3-x}{3x(x - 3)} = -\frac{x-3}{3x(x-3)}
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  4. #4
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    How does one get that fancy math writing?
    It sure beats how I did it... Is there a page explaining the syntax?
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  5. #5
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    Quote Originally Posted by Lord Voldemort View Post
    How does one get that fancy math writing?
    It sure beats how I did it... Is there a page explaining the syntax?
    Click on the fifth link in my signature.
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