\(MCD:R_1nt\left[\left(R_2ntR_3\right)//R_4\right]nt\left(R_5//R_6\right)\)
Ta có: \(\left\{{}\begin{matrix}R_{234}=\dfrac{R_{23}\cdot R_4}{R_{23}+R_4}=\dfrac{\left(10+5\right)\cdot15}{10+5+15}=7,5\Omega\\R_{56}=\dfrac{R_5\cdot R_6}{R_5+R_6}=\dfrac{20\cdot30}{20+30}=12\Omega\end{matrix}\right.\)
Điện trở tương đương:
\(R_{td}=R_1+R_{234}+R_{56}=1+7,5+12=20,5\Omega\)