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Math Help - solving using algebra - is this correct?

  1. #1
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    solving using algebra - is this correct?

    (2x)^2/(.86-x)(.72-x)^3 = 4.5 x 10^-5 x is negligible so the answer I got for x was .0018


    can anybody show me how to arrive at the correct answer using a step by step explanation of the algebra. I multiplied .86 by (.72)^3 and multiplied this amount by 4.5 x 10^-5. Then I took the square root of this and 2x^2 and divided by 2 to get .0018. Can anyone show me where I went wrong? Any input would be greatly appreciated. thank you.
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  2. #2
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    Quote Originally Posted by confused20 View Post
    (2x)^2/(.86-x)(.72-x)^3 = 4.5 x 10^-5 x is negligible so the answer I got for x was .0018


    can anybody show me how to arrive at the correct answer using a step by step explanation of the algebra. I multiplied .86 by (.72)^3 and multiplied this amount by 4.5 x 10^-5. Then I took the square root of this and 2x^2 and divided by 2 to get .0018. Can anyone show me where I went wrong? Any input would be greatly appreciated. thank you.
     <br />
\frac{(2x)^2}{(.86-x)(.72-x)^3} = 4.5 \times 10^{-5} x<br />

    when rearranged gives a quartic in x. What techniques do you have available for solving a quartic?

    (It has two real roots and two complex roots, the real roots are close to 3.8\times  10^{-6} and 45.6)

    RonL
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