Question

Mình cần gấp ạ

Answer 1

R1 nt (R2//Rx)

\(\Rightarrow Rtd=R1+\dfrac{R2Rx}{R2+Rx}=R+\dfrac{R.R}{R+R}=R+\dfrac{R^2}{2R}=R+\dfrac{R}{2}=\dfrac{3R}{2}=120\Rightarrow R=80\Omega\)