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Math Help - Simplifying Rational Powers

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    Simplifying Rational Powers

    Bah, okay.

    I'm trying to find a common denominator right now for this part of the problem:

    4/3-5/6

    Don't I multiply the denominators together? Thus making it?


    24/18-15/18

    Now since I can subtract the numerators it means I get 9. 9/18 = 1/2

    That ends up as the right answer for the exponent of this: 12x^1/2/y^4/3

    However, in the solution it baffles me because they got the following:

    = (4*3)x^4/3-5/6/y^4/3

    = 12x^8/6-5/6/y^4/3

    It looks like they just multiplied it by two, but I didn't think that was how you got a common denominator...

    = 12x^1/2/y^4/3
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    Quote Originally Posted by A Beautiful Mind View Post
    Bah, okay.

    I'm trying to find a common denominator right now for this part of the problem:

    4/3-5/6

    Don't I multiply the denominators together? Thus making it?


    24/18-15/18

    Now since I can subtract the numerators it means I get 9. 9/18 = 1/2

    That ends up as the right answer for the exponent of this: 12x^1/2/y^4/3

    However, in the solution it baffles me because they got the following:

    = (4*3)x^4/3-5/6/y^4/3

    = 12x^8/6-5/6/y^4/3

    It looks like they just multiplied it by two, but I didn't think that was how you got a common denominator...

    = 12x^1/2/y^4/3
    Think what the lowest common denominator of 3 and 6 is (it's not 18, nor 12)
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  3. #3
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    Quote Originally Posted by A Beautiful Mind View Post
    Bah, okay.

    I'm trying to find a common denominator right now for this part of the problem:

    4/3-5/6

    Don't I multiply the denominators together? Thus making it?
    No. If the two denominators are relatively prime, then yes, you would multiply the denominators together. But here, one number is a multiple of another. In that case, the common denominator would simply be the bigger number.

    I'm aware of two methods to finding LCD's. This site explains both: How To Find The Least Common Denominator (LCD) .


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