30 10V 32 52 i=? 20V/ -2 42 5V i=3-(-2)=5A u=10-20-5=-15/ 3. =? i=? 4V 32 N大 32 1A + 5V 5V 3i-4=5 u=5+7=12V i=31i = 3− (−2) = 5A 3A − 2A i = ? 3 3 5 1 4 1。 u = 10− 20− 5 = −15V + − 5V − + u = ? − + 10V − + 20V 2。 + + - - 4V 5V i =? 3. + -+ - - 4V 5V 1A + - u =? 4. i A i 3 3 4 5 = − = u = 5+ 7 =12V 3 3