(1) RL=U²/P=6²/3=12Ω
(2) I=P/U=3/6=0.5A
(3) U1=U总-UL=8-6=2V R1=UI/I=2/0.5=4Ω
(4)P1=I²R1=(0.5A)²X4Ω=1W