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Math Help - Express R2 as a function of x

  1. #1
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    Express R2 as a function of x

    1/R=1/R1+1/R2

    The total is 1.2, R1 is x.
    I got down to 1/R= R1+R2/R1*R2. But from there I'm lost any pointers? Thanks

    Oh and the answer is 1.2x/x-1.2 I don't know how to get there though.
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  2. #2
    Senior Member tukeywilliams's Avatar
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     \frac{1}{1.2} = \frac{1}{x} + \frac{1}{R_2}

     \frac{1}{R_2} = \frac{1}{1.2} - \frac{1}{x}

     \frac{1}{R_2} = \frac{x - 1.2}{1.2x}

     R_2 = \frac{1.2x}{x-1.2}
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  3. #3
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    Quote Originally Posted by tukeywilliams View Post
     \frac{1}{1.2} = \frac{1}{x} + \frac{1}{R_2}

     \frac{1}{R_2} = \frac{1}{1.2} - \frac{1}{x}

     \frac{1}{R_2} = \frac{x - 1.2}{1.2x}

     R_2 = \frac{1.2x}{x-1.2}
    how did you get from this part
     \frac{1}{R_2} = \frac{x - 1.2}{1.2x}
    to this part

     R_2 = \frac{1.2x}{x-1.2}
    thank you so much for the help
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  4. #4
    Senior Member tukeywilliams's Avatar
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    I took the reciprocal.
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  5. #5
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    Quote Originally Posted by tukeywilliams View Post
    I took the reciprocal.
    of course.. man I'm stupid
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