Theo đề ta có:
\(\dfrac{1}{R_{tđ}}=\dfrac{n}{\dfrac{R}{s}}\Rightarrow\dfrac{1}{R_{tđ}}=\dfrac{5}{\dfrac{30}{5}}\)
\(\Rightarrow1.\dfrac{30}{5}=R_{đt}.5\)
\(\Rightarrow R_{tđ}=\dfrac{30}{5}:5\Rightarrow R_{tđ}=\dfrac{30}{25}=1,2\) \(\Omega\)
Vậy:.............................