... Tớnh c z = - 3i 0 ,25 Khi ú | z | 42 (3) 2 0 ,25 3b Phng trỡnh ó cho tng ng 32 x 4.3x 45 0 ,25 0,5 t t 3x t , (t 0) ta c t 4t 45 Do t>0 nờn ta chn t=9, ú t 0 ,25 3x 32 x Vy phng ... 0 Tớnh A dx x Tớnh B x2 x3 dx 0 ,25 0 ,25 x2 dx t x3 t x3 t x dx tdt x 0 ,25 t 3 2 i cn x t Khi ú B dt dt t t 31 3 Vy I A B 1,0 28 3 0 ,25 * Ta cú mt cu (S) cú ta tõm ... b ) T gi thit suy a bi (2 3i )( a bi ) 9i (1,0) a 3b a a 3b (3a 3b)i 1- 9i Do ú z i 3a 3b b 0 ,25 Ta cú w z z i 2(2 i ) i Suy w 72 12 50 0 ,25 3x b) Phng...