B\u00e0i 1 (trang 135 SGK Gi\u1ea3i t\u00edch 12):\u00a0Th\u1ef1c hi\u1ec7n c\u00e1c ph\u00e9p t\u00ednh sau:<\/strong><\/span><\/p>\n a) (3-5i)+(2+4i)<\/strong><\/span><\/p>\n b) (-2-3i)+(-1-7i)<\/strong><\/span><\/p>\n c) (4+3i)-(5-7i)<\/strong><\/span><\/p>\n d) (2-3i)-(5-4i)<\/strong><\/span><\/p>\n L\u1eddi gi\u1ea3i:<\/b><\/p>\n a) Ta c\u00f3: (3-5i)+(2+4i)=(3+2)+(-5+4)i=5-i<\/p>\n b) Ta c\u00f3: (-2-3i)+(-1-7i)=(-2-1)+(-3-7)i=-3-10i<\/p>\n c) Ta c\u00f3: (4+3i)-(5-7i)=(4-5)+(3-(-7))i=-1+10i<\/p>\n d) Ta c\u00f3: (2-3i)-(5-4i)=(2-5)+(-3+4)i=-3+i<\/p>\n B\u00e0i 2 (trang 136 SGK Gi\u1ea3i t\u00edch 12):\u00a0T\u00ednh \u03b1+ \u03b2,\u03b1- \u03b2 v\u1edbi:<\/strong><\/span><\/p>\n a) \u03b1=3, \u03b2=2i<\/strong><\/span><\/p>\n b) \u03b1=1-2i, \u03b2=6i<\/strong><\/span><\/p>\n c) \u03b1=5i, \u03b2=-7i<\/strong><\/span><\/p>\n d) \u03b1=15; \u03b2=4-2i<\/strong><\/span><\/p>\n L\u1eddi gi\u1ea3i:<\/b><\/p>\n a) Ta c\u00f3: (3) + (2i) = 3 + 2i ;\u00a0\u00a0\u00a0\u00a0(3) – (2i) = 3 – 2i<\/p>\n b) Ta c\u00f3: (1 – 2i) + (6i) = 1 + 4i;\u00a0\u00a0\u00a0\u00a0(1 – 2i) – (6i) = 1 – 8i<\/p>\n c) Ta c\u00f3: (5i) + (-7i) = -2i;\u00a0\u00a0\u00a0\u00a0(5i) – (-7i) = 12i<\/p>\n d) Ta c\u00f3: (15) + (4 – 2i) = 19 – 2i ;\u00a0\u00a0\u00a0\u00a0(15) – (4 – 2i) = 11 + 2i<\/p>\n B\u00e0i 3 (trang 136 SGK Gi\u1ea3i t\u00edch 12):\u00a0Th\u1ef1c hi\u1ec7n c\u00e1c ph\u00e9p t\u00ednh sau:<\/strong><\/span><\/p>\n a) (3-2i)(2-3i)<\/strong><\/span><\/p>\n b) (-1+i)(3+7i)<\/strong><\/span><\/p>\n c) (5(4+3i)<\/strong><\/span><\/p>\n d) (-2-5i)4i<\/strong><\/span><\/p>\n L\u1eddi gi\u1ea3i:<\/b><\/p>\n a) Ta c\u00f3: (3-2i)(2-3i)=(3.2-2.3)+(-3.3-2.2)i=-13i<\/p>\n b) Ta c\u00f3: (-1+i)(3+7i)=(-1.3-1.7)+(-1.7+1.3)i=-10-4i<\/p>\n c) Ta c\u00f3: (5(4+3i)=5.4+5.3i=20+15i<\/p>\n d) Ta c\u00f3: (-2-5i)4i=(-2.0+5.4)+(2.4-5.0)i=20-8i<\/p>\n B\u00e0i 4 (trang 136 SGK Gi\u1ea3i t\u00edch 12):\u00a0T\u00ednh i3<\/sup>,i4<\/sup>;i5<\/sup>. N\u00eau c\u00e1ch t\u00ednh in<\/sup>\u00a0v\u1edbi n l\u00e0 s\u1ed1 t\u1ef1 nhi\u00ean t\u00f9y \u00fd:<\/strong><\/span><\/p>\n L\u1eddi gi\u1ea3i:<\/b><\/p>\n *Ta c\u00f3: i3<\/sup>\u00a0= i2<\/sup>.i= – 1i = -1<\/p>\n *Ta c\u00f3: i4<\/sup>\u00a0= i2<\/sup>.i2<\/sup>\u00a0= -1.(-1) = 1<\/p>\n *Ta c\u00f3: i5<\/sup>\u00a0= i4<\/sup>.i = 1.i = i<\/p>\n *Ta c\u00f3: i4<\/sup>\u00a0= 1<\/p>\n *V\u1edbi k nguy\u00ean d\u01b0\u01a1ng thig i4<\/sup>k = (i4<\/sup>\u00a0)k<\/sup>\u00a0= 1k<\/sup>\u00a0= 1<\/p>\n V\u1eady v\u1edbi s\u1ed1 t\u1ef1 nhi\u00ean t\u00f9y \u00fd, chia n cho 4 \u0111\u01b0\u1ee3c th\u01b0\u01a1ng l\u00e0 k d\u01b0 l\u00e0 r ngh\u0129a l\u00e0:<\/p>\n n=4k+r,k \u2208N,r=0,1,2,3<\/p>\n Khi \u0111\u00f3: in<\/sup>\u00a0= i(4k + r)<\/sup>\u00a0= i4<\/sup>k.ir<\/sup>\u00a0= 1.ir<\/sup>\u00a0= ir<\/sup><\/p>\n B\u00e0i 5 (trang 136 SGK Gi\u1ea3i t\u00edch 12):\u00a0T\u00ednh:<\/strong><\/span><\/p>\n a) (2+3i)2<\/sup><\/strong><\/span><\/p>\n b) (2+3i)3<\/sup><\/strong><\/span><\/p>\n L\u1eddi gi\u1ea3i:<\/b><\/p>\n Ta c\u00f3: (2+3i)2<\/sup>=(2+3i)(2+3i)=(22<\/sup>-33<\/sup>\u00a0)+(2.2.3)i=-5+12i<\/p>\n T\u1ed5ng qu\u00e1t (a+bi)2<\/sup>=a2<\/sup>-b2<\/sup>+2abi<\/p>\n Ta c\u00f3: (2+3i)3<\/sup>\u00a0=(2+3i)<\/p>\n (2+3i)2<\/sup>=(-5+12i)(2+3i)<\/p>\n =(-5.2-12.3)+(-5.3+12.2)i=-49+9i<\/p>\n C\u00f3 th\u1ec3 t\u00ednh ((2+3i)3<\/sup>\u00a0b\u1eb1ng c\u00e1ch \u00e1p d\u1ee5ng h\u1eb3ng \u0111\u1eb3ng th\u1ee9c<\/p>\n (2+3i)3<\/sup>=23<\/sup>+3.22<\/sup>.3i+3.2.(3i)2<\/sup>+(3i)3<\/sup><\/p>\n =(8-54)+(36-27)i=-46+9i<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":" B\u00e0i 1 (trang 135 SGK Gi\u1ea3i t\u00edch 12):\u00a0Th\u1ef1c hi\u1ec7n c\u00e1c ph\u00e9p t\u00ednh sau: a) (3-5i)+(2+4i) b) (-2-3i)+(-1-7i) c) (4+3i)-(5-7i) d) (2-3i)-(5-4i) L\u1eddi gi\u1ea3i: a) Ta c\u00f3: (3-5i)+(2+4i)=(3+2)+(-5+4)i=5-i b) Ta c\u00f3: (-2-3i)+(-1-7i)=(-2-1)+(-3-7)i=-3-10i c) Ta c\u00f3: (4+3i)-(5-7i)=(4-5)+(3-(-7))i=-1+10i d) Ta c\u00f3: (2-3i)-(5-4i)=(2-5)+(-3+4)i=-3+i B\u00e0i 2 (trang 136 SGK Gi\u1ea3i t\u00edch 12):\u00a0T\u00ednh \u03b1+ \u03b2,\u03b1- \u03b2 v\u1edbi: a) \u03b1=3, \u03b2=2i b) […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false,"tdm_status":"","tdm_grid_status":""},"categories":[1298],"tags":[1377,1356,1355],"yoast_head":"\n