35 4 3.5in1+10 解得 43.75A 4×43.75 0.1I 5A 10n i3=0.1in=0.1×(-5)=-0.5A 选外层回路列KVL方程 20in+1×in2+420-U=0 题3-12图 从中解出 U=20×(-5)+1×(-43.75)+420=27625v