от Добромир Глухаров » 21 Окт 2013, 17:01
[tex]\|\begin{array}{l}0,7(R_A+2R_B).10.10^{-9}=\frac{1}{4,8.10^3}|.\frac{10^9}{7}\\\frac{R_A+R_B}{R_A+2R_B}=0,84\end{array}[/tex]
[tex]\|\begin{array}{l}R_A+2R_B=\frac{10^9}{4,8.7.10^3}=\frac{10^6}{33,6}\\\frac{R_A+R_B}{\frac{10^6}{33,6}}=0,84|.\frac{10^6}{33,6}\end{array}[/tex]
[tex]\|\begin{array}{l}R_A+2R_B=\frac{10^6}{33,6}\\R_A+R_B=\frac{0,84}{33,6}.10^6\end{array}[/tex]
[tex]R_A+2R_B-(R_A+R_B)=\frac{10^6}{33,6}-\frac{0,84.10^6}{33,6}=\frac{1-0,84}{33,6}.10^6=\frac{0,16}{33,6}.10^6[/tex]
[tex]R_B=\frac{0,16}{33,6}.10^6=\frac{16}{33,6}.10^4=\frac{10^4}{2,1}\approx 4\ 761,9[/tex]
[tex]R_A=\frac{0,84}{33,6}.10^6-R_B=\(\frac{84}{33,6}-\frac{1}{2,1}\).10^4=\(\frac{21}{8,4}-\frac{4}{8,4}\).10^4=\frac{21-4}{8,4}.10^4=\frac{17}{8,4}.10^4\approx 20\ 238[/tex]