Параллельное соединение двух резисторов. Дано: R₂=1,2 kΩ, Iобщ=8 mA, P₁=18 mW. Найти: U,...

$I_{o}=I_{1}+I_{2},\\ U=U_{1}=U_{2},\\ P_{1}=I_{1}U, I_{1}=\frac{P_{1}}{U},\\ I_{2}=\frac{U}{R_{2}},\\ I_{o}=\frac{P_{1}}{U}+\frac{U}{R_{2}}, *UR_{2}\\ U^{2}-I_{o}R_{2}U+P_{1}R_{2}=0.\\ U^{2}-9.6U+21.6=0,\\ 5U^{2}-48U+108=0,\\ D=144,\\$
вариант 1
$U=\frac{48+12}{10}=6(B),\\ I_{2}=\frac{6}{1200}=5mA,\\ I_{1}=8mA-5mA=3mA,\\ R_{1}=\frac{6}{0.003}=2kOm,\\ P_{2}=0.005*6=30mW,\\ P_{o}=6*0.008=48mW$
вариант 2
$U=\frac{48-12}{10}=3.6(B),\\ I_{2}=\frac{3.6}{1200}=3mA,\\ I_{1}=8mA-3mA=5mA,\\ R_{1}=\frac{3.6}{0.005}=720Om,\\ P_{2}=0.003*3.6=10.8mW,\\ P_{o}=3.6*0.008=28.8mW$