U=9 B R1=262.5 Ом R2=750 Ом R3=250 Ом
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R23=R2*R3/(R2+R3)=750*250/(750+250)=187.5 Ом
R=R1+R23=262.5+187.5=450 Ом (общее сопротивление цепи)
I=I1=U/R=9/450=0.02 A
U1=I1*R1=0.02*262.5=5.25 B
U2=U3=I*R23=0.02*187.5=3.75 B
I2=U2/R2=3.75/750=0.005 A
I3=U3/R3=3.75/250=0.015 A
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