Помогите с 4-м и 5-м вариантами

Вариант 4 [latex] \frac{1}{R_{2-5}}= \frac{1}{R_{2}+R_{3}}+ \frac{1}{R_{4}+R_{5}}= \frac{1}{6+6} + \frac{1}{7+5}= \frac{1}{12} + \frac{1}{12}= \frac{2}{12} = \frac{1}{6} [/latex] [latex]R_{2-5}=6[/latex] Ом [latex]R=R_{1}+R_{2-5}=1+6=7[/latex] Ом [latex]I= \frac{U}{R} [/latex] [latex]I= \frac{42}{7}=6 [/latex] A Вариант 5 [latex] \frac{1}{R_{1-2}}= \frac{1}{R_{1}}+ \frac{1}{R_{2}}= \frac{1}{3}+ \frac{1}{6}} =\frac{1}{2} [/latex] [latex]R_{1-2}=2[/latex] Ом [latex]R_{1-3}=R_{1-2}+R_{3}=2+2=4[/latex] Ом [latex] \frac{1}{R}= \frac{1}{R_{1-3}}+ \frac{1}{R_{4}}+ \frac{1}{R_{5}} = \frac{1}{4} + \frac{1}{12} + \frac{1}{6}= \frac{6}{12}= \frac{1}{2} [/latex] [latex]R=2[/latex] Ом [latex]I= \frac{U}{R} [/latex] [latex]I= \frac{18}{2}=9 [/latex] A