... c´o: 1/ nˆe´u z 1 = r 1 eiϕ 1 , z2= r2eiϕ2th`ız 1 z2= r 1 r2ei(ϕ 1 +ϕ2), (1. 12)z 1 /z2=r 1 r2ei(ϕ 1 −ϕ2), (1. 13)2/ nˆe´u z = reiϕth`ızn= rneinϕ, (1. 14)n√z ... chı’khia2+ b2− 1 (a +1) 2+ b2=0⇐⇒ a2+ b2 =1. B`AI TˆA.PT´ınh 1. (1 + i)8− 1 (1 − i)8 +1 · (DS. 15 17 )2. (1+ 2i)3+ (1 2i)3(2 − i)2− (2 + i)2· (DS. − 11 4i)3.(3 − 4i)(2 ... ·i2···i99· i 10 0= 1. 2+T`ım sˆo´nguyˆen n nˆe´u:a) (1 + i)n= (1 i)n;b) 1+ i√2n+ 1 − i√2n=0. Gia ’i. 1 +Ta c´o i0 =1, i 1 = i, i2= 1, i3= −i, i4 =1, i5= i v`agi´a...