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$$0.449=\frac{e^{b_1}}{e^{b_1}+e^{b_2}+e^{b_3}}$$ $$0.335=\frac{e^{b_2}}{e^{b_1}+e^{b_2}+e^{b_3}}$$ $$0.216=\frac{e^{b_3}}{e^{b_1}+e^{b_2}+e^{b_3}}$$

My attempt: $$\ln(0.449)=b_1+\ln(.)$$ $$\ln(0.335)=b_2+\ln(.)$$ $$\ln(0.216)=b_3+\ln(.)$$ where $\ln(.)=\ln(e^{b_1}+e^{b_2}+e^{b_3})$

But then I get stuck and would like help on how to solve this? What are the values for $b_1$, $b_2$ and $b_3$?

Would like a step-by-step explanation. Thanks.

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    $\begingroup$ substitute $x_i=exp(b_i)$. $\endgroup$
    – YJT
    Aug 20, 2020 at 12:36
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    $\begingroup$ It would be better if you wrote the whole problem out using latex with MathJax, rather than relying on a picture. This makes your question easier for others to edit. For example in the first three lines the letter "o" should be the number $0$. See: math.meta.stackexchange.com/questions/5020/… $\endgroup$
    – halrankard
    Aug 20, 2020 at 12:40
  • $\begingroup$ YJT's hint looks good to me. Use that and the problem should become much more manageable. $\endgroup$
    – Matti P.
    Aug 20, 2020 at 12:50

1 Answer 1

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There are infinitely many solutions. To prove this, let $A=e^{b_1}, B=e^{b_2}, C=e^{b_3}$. $A,B$ and $C$ all must be positive numbers. Then the system of equations becomes: $$0.449=\frac{A}{A+B+C}$$ $$0.335=\frac{B}{A+B+C}$$ $$0.216=\frac{C}{A+B+C}$$

There are infinitely many solutions, for which we have one degree of freedom. Our solutions are: $$A=0.449D\Rightarrow b_1=\ln(0.449)+\ln(D) = \ln(0.449) + E$$ $$B=0.335D\Rightarrow b_2=\ln(0.335)+\ln(D) = \ln(0.335) + E$$ $$C=0.216D\Rightarrow b_3=\ln(0.216)+\ln(D) = \ln(0.216) + E$$ $D$ can take on any positive value, and $E=\ln(D)$ can take on any real value.

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