$R_1ntR_2$
$I_1=I_2$
$⇒\dfrac{U_1}{R_1}=\dfrac{U_2}{R_2}$
$⇒\dfrac{U_1}{3R_2}=\dfrac{U_2}{R_2}$
$⇒U_1-3U_2=0$
$U_1+U_2=U=60$
Từ trên ta có hệ sau:
\(\left\{ \begin{array}{l}U_1+U_2=60\\U_1-3U_2=0\end{array} \right.\)
$⇒$\(\left\{ \begin{array}{l}U_1=45V\\U_2=15V\end{array} \right.\)