{"segment":[{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["66"]]],"list":[{"point":10,"width":50,"content":"","type_input":"","ques":"Cho tr\u01b0\u1edbc 12 \u0111i\u1ec3m trong \u0111\u00f3 kh\u00f4ng c\u00f3 3 \u0111i\u1ec3m n\u00e0o th\u1eb3ng h\u00e0ng. V\u1ebd c\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng \u0111i qua c\u00e1c c\u1eb7p \u0111i\u1ec3m. H\u1ecfi v\u1ebd \u0111\u01b0\u1ee3c t\u1ea5t c\u1ea3 bao nhi\u00eau \u0111\u01b0\u1eddng th\u1eb3ng? <br\/> \u0110\u00e1p \u00e1n l\u00e0: _input_ \u0111\u01b0\u1eddng th\u1eb3ng ","hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> L\u1ea5y m\u1ed9t \u0111i\u1ec3m n\u1ed1i v\u1edbi n - 1 \u0111i\u1ec3m kh\u00e1c ta \u0111\u01b0\u1ee3c n - 1 \u0111\u01b0\u1eddng th\u1eb3ng <br\/> Qua n \u0111i\u1ec3m trong \u0111\u00f3 kh\u00f4ng c\u00f3 3 \u0111i\u1ec3m n\u00e0o th\u1eb3ng h\u00e0ng v\u1ebd \u0111\u01b0\u1ee3c: <br\/> $\\dfrac{n . (n - 1)}{2}$ \u0111\u01b0\u1eddng th\u1eb3ng <br\/> (V\u00ec m\u1ed7i \u0111\u01b0\u1eddng th\u1eb3ng \u0111\u00e3 \u0111\u01b0\u1ee3c t\u00ednh 2 l\u1ea7n n\u00ean ta ph\u1ea3i \u0111em k\u1ebft qu\u1ea3 chia 2) <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i: <\/span><br\/> Qua hai \u0111i\u1ec3m lu\u00f4n v\u1ebd \u0111\u01b0\u1ee3c 1 \u0111\u01b0\u1eddng th\u1eb3ng <br\/> Qua 12 \u0111i\u1ec3m v\u1ebd \u0111\u01b0\u1ee3c t\u1ea5t c\u1ea3 s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng l\u00e0: <br\/> $\\dfrac{12 . (12 - 1)}{2} = 66$ (\u0111\u01b0\u1eddng th\u1eb3ng) <br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 66 <\/span> <br\/> <span class='basic_left'> <span class='basic_green'><i> L\u01b0u \u00fd: +) Sai l\u1ea7m hay m\u1eafc ph\u1ea3i khi l\u00e0m b\u00e0i to\u00e1n d\u1ea1ng n\u00e0y l\u00e0 khi t\u00ednh s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c ta kh\u00f4ng \u0111em k\u1ebft qu\u1ea3 chia 2 <br\/> +) Khi b\u00e0i to\u00e1n cho n \u0111i\u1ec3m m\u00e0 kh\u00f4ng n\u00f3i g\u00ec th\u00eam ta hi\u1ec3u \u0111\u00f3 l\u00e0 \u0111i\u1ec3m ph\u00e2n bi\u1ec7t<\/span> "}]}],"id_ques":1941},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["132"]]],"list":[{"point":10,"width":50,"content":"","type_input":"","ques":"Gi\u1ea3i b\u00f3ng \u0111\u00e1 v\u00f4 \u0111\u1ecbch qu\u1ed1c gia h\u1ea1ng chuy\u00ean nghi\u1ec7p c\u00f3 12 \u0111\u1ed9i tham gia \u0111\u1ea5u v\u00f2ng tr\u00f2n 2 l\u01b0\u1ee3t \u0111i v\u00e0 v\u1ec1. T\u00ednh t\u1ed5ng s\u1ed1 tr\u1eadn \u0111\u1ea5u? <br\/> \u0110\u00e1p \u00e1n l\u00e0: _input_ tr\u1eadn \u0111\u1ea5u ","hint":"M\u1ed7i \u0111\u1ed9i \u0111\u1ec1u \u0111\u1ea5u v\u1edbi 1 \u0111\u1ed9i kh\u00e1c 2 l\u01b0\u1ee3t \u0111i v\u00e0 v\u1ec1 n\u00ean m\u1ed7i \u0111\u1ed9i \u0111\u1ec1u \u0111\u1ea5u v\u1edbi 1 \u0111\u1ed9i kh\u00e1c 2 tr\u1eadn \u0111\u1ea5u","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> T\u00ednh s\u1ed1 tr\u1eadn \u0111\u1ea5u 1 \u0111\u1ed9i \u0111\u1ea5u v\u1edbi 11 \u0111\u1ed9i c\u00f2n l\u1ea1i <br\/> <b> B\u01b0\u1edbc 2: <\/b> T\u00ednh s\u1ed1 tr\u1eadn \u0111\u1ea5u c\u00e1c \u0111\u1ed9i \u0111\u1ea5u m\u00e0 12 \u0111\u1ed9i \u0111\u00e1 2 l\u01b0\u1ee3t \u0111i v\u00e0 v\u1ec1 <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i: <\/span><br\/> N\u1ebfu g\u1ecdi 12 \u0111\u1ed9i b\u00f3ng \u0111\u00f3 l\u00e0 \u0111\u1ed9i 1, \u0111\u1ed9i 2, ..., \u0111\u1ed9i 12 <br\/> V\u00ec m\u1ed7i \u0111\u1ed9i \u0111\u1ec1u \u0111\u1ea5u v\u1edbi 1 \u0111\u1ed9i kh\u00e1c <br\/> S\u1ed1 tr\u1eadn \u0111\u1ea5u \u0111\u1ed9i 1 \u0111\u00e1 v\u1edbi 11 \u0111\u1ed9i c\u00f2n l\u1ea1i l\u00e0: 1. 11 = 11 (tr\u1eadn \u0111\u1ea5u) <br\/> 12 \u0111\u1ed9i s\u1ebd \u0111\u1ea5u t\u1ea5t c\u1ea3: 11 . 12 = 132 (tr\u1eadn \u0111\u1ea5u) <br\/> Trong \u0111\u00f3 m\u1ed7i \u0111\u1ed9i \u0111\u1ec1u \u0111\u00e3 \u0111\u00e1 v\u1edbi 11 \u0111\u1ed9i kh\u00e1c 2 l\u01b0\u1ee3t \u0111i v\u00e0 v\u1ec1 <br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 132 <\/span> <br\/> <span class='basic_left'> <span class='basic_green'> <i> L\u01b0u \u00fd: <\/b> \u1ede b\u00e0i to\u00e1n n\u00e0y khi t\u00ednh s\u1ed1 tr\u1eadn \u0111\u1ea5u ta kh\u00f4ng chia 2 v\u00ec m\u1ed7i \u0111\u1ed9i \u0111\u1ec1u \u0111\u00e1 v\u1edbi 1 \u0111\u1ed9i kh\u00e1c 2 tr\u1eadn l\u01b0\u1ee3t \u0111i v\u00e0 v\u1ec1 <\/i><\/span> "}]}],"id_ques":1942},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["9"]]],"list":[{"point":10,"width":50,"content":"","type_input":"","ques":"Cho tr\u01b0\u1edbc m\u1ed9t s\u1ed1 \u0111i\u1ec3m trong \u0111\u00f3 kh\u00f4ng c\u00f3 3 \u0111i\u1ec3m n\u00e0o th\u1eb3ng h\u00e0ng. V\u1ebd c\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng \u0111i qua c\u00e1c c\u1eb7p \u0111i\u1ec3m \u0111\u00f3. Bi\u1ebft t\u1ed5ng s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c l\u00e0 36 \u0111\u01b0\u1eddng th\u1eb3ng. T\u00ednh s\u1ed1 \u0111i\u1ec3m cho tr\u01b0\u1edbc \u0111\u00f3? <br\/> \u0110\u00e1p \u00e1n l\u00e0: _input_ \u0111i\u1ec3m","hint":"D\u1ef1a v\u00e0o c\u00f4ng th\u1ee9c $\\dfrac{n . (n - 1)}{2}$ \u0111\u1ec3 t\u00ednh s\u1ed1 \u0111i\u1ec3m, n ch\u00ednh l\u00e0 s\u1ed1 \u0111i\u1ec3m c\u1ea7n t\u00ecm. ","explain":" <span class='basic_green'>B\u00e0i gi\u1ea3i: <\/span><br\/> V\u00ec s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c qua n \u0111i\u1ec3m trong \u0111\u00f3 kh\u00f4ng c\u00f3 3 \u0111i\u1ec3m n\u00e0o kh\u00f4ng th\u1eb3ng h\u00e0ng l\u00e0: <br\/> $\\dfrac{n . (n - 1)}{2}$ <br\/> Bi\u1ebft s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c l\u00e0 36 \u0111\u01b0\u1eddng th\u1eb3ng n\u00ean ta c\u00f3: <br\/> $\\begin{align*} \\\\ \\dfrac{n . (n - 1)}{2} &= 36 \\\\ n . (n - 1) &= 36 . 2 \\\\ n . (n - 1) &= 72 \\\\ n . (n - 1) &= 9 . 8 \\end{align*}$ <br\/> $\\Rightarrow$ n = 9, n - 1 = 8 <br\/> V\u1eady c\u00f3 t\u1ea5t c\u1ea3 9 \u0111i\u1ec3m cho tr\u01b0\u1edbc <br\/><span class='basic_pink'> S\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 9 <\/span> <br\/> <span class='basic_left'><span class='basic_green'> <i> L\u01b0u \u00fd: V\u1edbi d\u1ea1ng b\u00e0i y\u00eau c\u1ea7u t\u00ecm n \u0111i\u1ec3m ph\u00e2n bi\u1ec7t trong \u0111\u00f3 kh\u00f4ng c\u00f3 3 \u0111i\u1ec3m n\u00e0o th\u1eb3ng h\u00e0ng bi\u1ebft s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c l\u00e0 a \u0111\u01b0\u1eddng th\u1eb3ng ta l\u00e0m nh\u01b0 sau: $\\dfrac{n . (n - 1)}{2} = a$ <br\/> Trong \u0111\u00f3 a l\u00e0 s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng \u0111\u00e3 bi\u1ebft, n l\u00e0 s\u1ed1 \u0111i\u1ec3m c\u1ea7n t\u00ecm <\/i><\/span> "}]}],"id_ques":1943},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00fang hay sai","title_trans":"","temp":"true_false","correct":[["t","f"]],"list":[{"point":10,"image":"","col_name":["Kh\u1eb3ng \u0111\u1ecbnh","\u0110\u00fang","Sai"],"arr_ques":[" N\u1ebfu 3 \u0111i\u1ec3m A, B, C th\u1eb3ng h\u00e0ng th\u00ec hai \u0111\u01b0\u1eddng th\u1eb3ng AB, AC tr\u00f9ng nhau"," N\u1ebfu hai \u0111\u01b0\u1eddng th\u1eb3ng AB, AC tr\u00f9ng nhau th\u00ec 3 \u0111i\u1ec3m A, B, C kh\u00f4ng th\u1eb3ng h\u00e0ng "],"hint":"V\u1ebd h\u00ecnh minh h\u1ecda","explain":["\u0110\u00daNG v\u00ec: <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/bai3/lv3/img\/H613_K101.png' \/><\/center> ","SAI v\u00ec: <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/bai3/lv3/img\/H613_K102.png' \/><\/center> "]}]}],"id_ques":1944},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":10,"ques":"Cho 5 \u0111i\u1ec3m A, B, C, D, E sao cho 3 \u0111i\u1ec3m A, B, C th\u1eb3ng h\u00e0ng; 3 \u0111i\u1ec3m B, C, D th\u1eb3ng h\u00e0ng; 3 \u0111i\u1ec3m B, C, E kh\u00f4ng th\u1eb3ng h\u00e0ng. V\u1ebd \u0111\u01b0\u1ee3c t\u1ea5t c\u1ea3 bao nhi\u00eau \u0111\u01b0\u1eddng th\u1eb3ng m\u1ed7i \u0111\u01b0\u1eddng th\u1eb3ng \u0111i qua \u00edt nh\u1ea5t hai \u0111i\u1ec3m (kh\u00f4ng k\u1ec3 \u0111\u01b0\u1eddng th\u1eb3ng tr\u00f9ng nhau)?","select":["A. 4 \u0111\u01b0\u1eddng th\u1eb3ng","B. 2 \u0111\u01b0\u1eddng th\u1eb3ng","C. 5 \u0111\u01b0\u1eddng th\u1eb3ng","D. 3 \u0111\u01b0\u1eddng th\u1eb3ng"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> X\u00e1c \u0111\u1ecbnh xem \u0111i\u1ec3m n\u00e0o n\u1eb1m ngo\u00e0i \u0111\u01b0\u1eddng th\u1eb3ng ch\u1ee9a c\u00e1c \u0111i\u1ec3m c\u00f2n l\u1ea1i <br\/> <b> B\u01b0\u1edbc 2: <\/b> V\u1ebd c\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng \u0111i qua c\u00e1c \u0111i\u1ec3m \u0111\u00f3, m\u1ed7i \u0111\u01b0\u1eddng th\u1eb3ng \u0111i qua \u00edt nh\u1ea5t hai \u0111i\u1ec3m <br\/> <b> B\u01b0\u1edbc 3: <\/b> \u0110\u1ebfm s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c v\u00e0 ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang <br\/> C\u00e1ch n\u00e0y ch\u1ec9 \u00e1p d\u1ee5ng \u0111\u01b0\u1ee3c n\u1ebfu s\u1ed1 \u0111i\u1ec3m \u0111\u00e3 cho l\u00e0 s\u1ed1 nh\u1ecf <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: <br\/> V\u00ec 3 \u0111i\u1ec3m A, B, C th\u1eb3ng h\u00e0ng n\u00ean 3 \u0111i\u1ec3m A, B, C c\u00f9ng thu\u1ed9c 1 \u0111\u01b0\u1eddng th\u1eb3ng (1) <br\/> 3 \u0111i\u1ec3m B, C, D th\u1eb3ng h\u00e0ng n\u00ean 3 \u0111i\u1ec3m B, C, D c\u00f9ng thu\u1ed9c 1 \u0111\u01b0\u1eddng th\u1eb3ng (2) <br\/> T\u1eeb (1) v\u00e0 (2) $\\Rightarrow$ 4 \u0111i\u1ec3m A, B, C, D c\u00f9ng thu\u1ed9c 1 \u0111\u01b0\u1eddng th\u1eb3ng (3) <br\/> 3 \u0111i\u1ec3m B, C, E kh\u00f4ng th\u1eb3ng h\u00e0ng m\u00e0 theo (3) 4 \u0111i\u1ec3m A, B, C, D c\u00f9ng thu\u1ed9c 1 \u0111\u01b0\u1eddng th\u1eb3ng <br\/> N\u00ean \u0111i\u1ec3m E n\u1eb1m ngo\u00e0i \u0111\u01b0\u1eddng th\u1eb3ng ch\u1ee9a c\u00e1c \u0111i\u1ec3m A, B, C, D <br\/> Ta c\u00f3 h\u00ecnh v\u1ebd: <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/bai3/lv3/img\/H613_K108.png' \/><\/center> <br\/> V\u1eady v\u1ebd \u0111\u01b0\u1ee3c t\u1ea5t c\u1ea3 5 \u0111\u01b0\u1eddng th\u1eb3ng qua 5 \u0111i\u1ec3m tr\u00ean <br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0: C <\/span> <br\/><span class='basic_left'><span class='basic_green'> <i> L\u01b0u \u00fd: V\u1edbi b\u00e0i t\u00ednh s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c qua n \u0111i\u1ec3m trong \u0111\u00f3 c\u00f3 a \u0111i\u1ec3m th\u1eb3ng h\u00e0ng ta l\u00e0m nh\u01b0 sau: <br\/> +) T\u00ednh s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c qua n \u0111i\u1ec3m \u0111\u00f3 (coi nh\u01b0 kh\u00f4ng c\u00f3 3 \u0111i\u1ec3m n\u00e0o th\u1eb3ng h\u00e0ng) <br\/> S\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng = $\\dfrac{n.(n - 1)}{2}$ <br\/> +) T\u00ednh s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c qua a \u0111i\u1ec3m th\u1eb3ng h\u00e0ng (coi nh\u01b0 ch\u00fang kh\u00f4ng th\u1eb3ng h\u00e0ng): <br\/> S\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng = $\\dfrac{a . (a - 1)}{2}$ <br\/> V\u00ec qua a \u0111i\u1ec3m th\u1eb3ng h\u00e0ng ta ch\u1ec9 v\u1ebd \u0111\u01b0\u1ee3c m\u1ed9t \u0111\u01b0\u1eddng th\u1eb3ng <br\/> +) T\u00ednh s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c qua n \u0111i\u1ec3m trong \u0111\u00f3 c\u00f3 a \u0111i\u1ec3m th\u1eb3ng h\u00e0ng: <br\/> S\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c = $\\dfrac{n . (n - 1)}{2} - \\dfrac{a.(a - 1)}{2} + 1$ <\/span>","column":2}]}],"id_ques":1945},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["5050"]]],"list":[{"point":10,"width":50,"content":"","type_input":"","ques":"Cho 101 \u0111\u01b0\u1eddng th\u1eb3ng trong \u0111\u00f3 b\u1ea5t c\u1ee9 hai \u0111\u01b0\u1eddng th\u1eb3ng n\u00e0o c\u0169ng c\u1eaft nhau, kh\u00f4ng c\u00f3 3 \u0111\u01b0\u1eddng th\u1eb3ng n\u00e0o \u0111\u1ed3ng quy. T\u00ednh s\u1ed1 giao \u0111i\u1ec3m?<br\/> \u0110\u00e1p \u00e1n l\u00e0: _input_ giao \u0111i\u1ec3m","hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> M\u1ed9t \u0111\u01b0\u1eddng th\u1eb3ng c\u1eaft n - 1 \u0111\u01b0\u1eddng th\u1eb3ng kh\u00e1c ta \u0111\u01b0\u1ee3c n - 1 giao \u0111i\u1ec3m <br\/> <br\/> n \u0111\u01b0\u1eddng th\u1eb3ng c\u1eaft nhau trong \u0111\u00f3 kh\u00f4ng c\u00f3 3 \u0111\u01b0\u1eddng th\u1eb3ng n\u00e0o \u0111\u1ed3ng quy ta \u0111\u01b0\u1ee3c: <br\/> $\\dfrac{n . (n - 1)}{2}$ (giao \u0111i\u1ec3m)<br\/> (V\u00ec m\u1ed7i giao \u0111i\u1ec3m \u0111\u00e3 \u0111\u01b0\u1ee3c t\u00ednh 2 l\u1ea7n n\u00ean ta ph\u1ea3i l\u1ea5y k\u1ebft qu\u1ea3 chia 2) <br\/> T\u00ednh s\u1ed1 giao \u0111i\u1ec3m c\u1ee7a 101 \u0111\u01b0\u1eddng th\u1eb3ng c\u1eaft nhau theo c\u00f4ng th\u1ee9c tr\u00ean <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i: <\/span><br\/> 101 \u0111\u01b0\u1eddng th\u1eb3ng c\u1eaft nhau ta \u0111\u01b0\u1ee3c s\u1ed1 giao \u0111i\u1ec3m l\u00e0: <br\/> $\\dfrac{101 . (101 - 1)}{2}$ = 5050 (giao \u0111i\u1ec3m) <br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 5050 <\/span> <br\/> <span class='basic_left'> <span class='basic_green'><i> L\u01b0u \u00fd: +) Sai l\u1ea7m hay m\u1eafc ph\u1ea3i khi l\u00e0m b\u00e0i to\u00e1n d\u1ea1ng n\u00e0y l\u00e0 khi t\u00ednh s\u1ed1 giao \u0111i\u1ec3m c\u00f3 \u0111\u01b0\u1ee3c ta kh\u00f4ng \u0111em k\u1ebft qu\u1ea3 chia 2 <br\/> +) Khi b\u00e0i to\u00e1n cho n \u0111\u01b0\u1eddng th\u1eb3ng m\u00e0 kh\u00f4ng n\u00f3i g\u00ec th\u00eam ta hi\u1ec3u \u0111\u00f3 l\u00e0 \u0111\u01b0\u1eddng th\u1eb3ng ph\u00e2n bi\u1ec7t <br\/> S\u1ed1 giao \u0111i\u1ec3m = $\\dfrac{n . (n - 1)}{2}$<\/span> "}]}],"id_ques":1946},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["40"]]],"list":[{"point":10,"width":50,"content":"","type_input":"","ques":"Cho n \u0111\u01b0\u1eddng th\u1eb3ng trong \u0111\u00f3 b\u1ea5t c\u1ee9 hai \u0111\u01b0\u1eddng th\u1eb3ng n\u00e0o c\u0169ng c\u1eaft nhau, kh\u00f4ng c\u00f3 3 \u0111\u01b0\u1eddng th\u1eb3ng n\u00e0o \u0111\u1ed3ng quy. Bi\u1ebft r\u1eb1ng s\u1ed1 giao \u0111i\u1ec3m c\u1ee7a c\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng \u0111\u00f3 l\u00e0 780 giao \u0111i\u1ec3m. T\u00ednh n? <br\/> \u0110\u00e1p \u00e1n l\u00e0 n = _input_ \u0111\u01b0\u1eddng th\u1eb3ng","hint":"D\u1ef1a v\u00e0o c\u00f4ng th\u1ee9c t\u00ednh s\u1ed1 giao \u0111i\u1ec3m \u0111\u1ec3 t\u00ecm s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng <br\/> S\u1ed1 giao \u0111i\u1ec3m = $\\dfrac{n . (n - 1)}{2}$","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> V\u00ec s\u1ed1 giao \u0111i\u1ec3m = $\\dfrac{n . (n - 1)}{2}$ <br\/> Bi\u1ebft s\u1ed1 giao \u0111i\u1ec3m l\u00e0 780 ta thay v\u00e0o c\u00f4ng th\u1ee9c tr\u00ean \u0111\u1ec3 t\u00ecm n <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i: <\/span><br\/> n \u0111\u01b0\u1eddng th\u1eb3ng c\u1eaft nhau trong \u0111\u00f3 kh\u00f4ng c\u00f3 3 \u0111\u01b0\u1eddng th\u1eb3ng n\u00e0o \u0111\u1ed3ng quy c\u00f3 t\u1ea5t c\u1ea3 s\u1ed1 giao \u0111i\u1ec3m l\u00e0: <br\/> $\\dfrac{n.(n - 1)}{2}$ <br\/> M\u00e0 s\u1ed1 giao \u0111i\u1ec3m l\u00e0 780 giao \u0111i\u1ec3m n\u00ean ta c\u00f3: <br\/> $\\begin{align*}\\dfrac{n.(n - 1)}{2} &= 780 \\\\ n . (n - 1) &= 780 . 2 \\\\ n . (n - 1) &= 1560 \\\\ n . (n - 1) &= 40 . 39 \\end{align*}$ <br\/> V\u1eady n = 40 hay 40 \u0111\u01b0\u1eddng th\u1eb3ng c\u1eaft nhau (trong \u0111\u00f3 kh\u00f4ng c\u00f3 3 \u0111\u01b0\u1eddng th\u1eb3ng n\u00e0o \u0111\u1ed3ng quy) th\u00ec t\u1ea1o ra 780 giao \u0111i\u1ec3m <br\/> <span class='basic_pink'>V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 40 <\/span> "}]}],"id_ques":1947},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["7"]]],"list":[{"point":10,"width":50,"content":"","type_input":"","ques":"Cho 20 \u0111i\u1ec3m trong \u0111\u00f3 c\u00f3 a \u0111i\u1ec3m th\u1eb3ng h\u00e0ng. C\u1ee9 hai \u0111i\u1ec3m ta v\u1ebd \u0111\u01b0\u1ee3c m\u1ed9t \u0111\u01b0\u1eddng th\u1eb3ng. T\u00ecm a bi\u1ebft v\u1ebd \u0111\u01b0\u1ee3c t\u1ea5t c\u1ea3 170 \u0111\u01b0\u1eddng th\u1eb3ng. <br\/> \u0110\u00e1p \u00e1n l\u00e0 a = _input_ \u0111i\u1ec3m","hint":"D\u1ef1a v\u00e0o c\u00f4ng th\u1ee9c t\u00ednh s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c: $\\dfrac{n . (n - 1)}{2}$","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> T\u00ednh s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c qua 20 \u0111i\u1ec3m (trong \u0111\u00f3 kh\u00f4ng c\u00f3 3 \u0111i\u1ec3m n\u00e0o th\u1eb3ng h\u00e0ng) <br\/> $\\dfrac{20 . (20 - 1)}{2}$ <br\/> <b> B\u01b0\u1edbc 2: <\/b> T\u00ednh s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng v\u1ebd \u0111\u01b0\u1ee3c qua a \u0111i\u1ec3m kh\u00f4ng th\u1eb3ng h\u00e0ng <br\/> $\\dfrac{a . (a - 1)}{2}$ <br\/> <b> B\u01b0\u1edbc 3: <\/b> V\u00ec qua a \u0111i\u1ec3m th\u1eb3ng h\u00e0ng ch\u1ec9 v\u1ebd \u0111\u01b0\u1ee3c 1 \u0111\u01b0\u1eddng th\u1eb3ng n\u00ean s\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng gi\u1ea3m \u0111i l\u00e0: <br\/> $\\dfrac{a . (a - 1)}{2} - 1$ \u0111\u01b0\u1eddng th\u1eb3ng <br\/> <b> B\u01b0\u1edbc 4: <\/b> T\u00ednh s\u1ed1 \u0111i\u1ec3m th\u1eb3ng h\u00e0ng c\u1ea7n t\u00ecm <br\/> V\u00ec ch\u1ec9 v\u1ebd \u0111\u01b0\u1ee3c 170 \u0111\u01b0\u1eddng th\u1eb3ng n\u00ean ta c\u00f3: $\\dfrac{20 . (20 - 1)}{2} - [\\dfrac{a.(a - 1)}{2} - 1] = 170$ <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i: <\/span><br\/> Gi\u1ea3 s\u1eed 20 \u0111i\u1ec3m tr\u00ean kh\u00f4ng c\u00f3 3 \u0111i\u1ec3m n\u00e0o th\u1eb3ng h\u00e0ng ta v\u1ebd \u0111\u01b0\u1ee3c: <br\/> $\\dfrac{20 . (20 - 1)}{2} = 190 $(\u0111\u01b0\u1eddng th\u1eb3ng) <br\/> Gi\u1ea3 s\u1eed a \u0111i\u1ec3m tr\u00ean kh\u00f4ng c\u00f3 3 \u0111i\u1ec3m n\u00e0o th\u1eb3ng h\u00e0ng ta v\u1ebd \u0111\u01b0\u1ee3c: <br\/> $\\dfrac{a. (a - 1)}{2}$ (\u0111\u01b0\u1eddng th\u1eb3ng) <br\/> Nh\u01b0ng th\u1ef1c t\u1ebf a \u0111i\u1ec3m tr\u00ean th\u1eb3ng h\u00e0ng n\u00ean ta ch\u1ec9 v\u1ebd \u0111\u01b0\u1ee3c 1 \u0111\u01b0\u1eddng th\u1eb3ng <br\/> S\u1ed1 \u0111\u01b0\u1eddng th\u1eb3ng gi\u1ea3m \u0111i l\u00e0: <br\/> $\\dfrac{a . (a - 1)}{2} - 1$ (\u0111\u01b0\u1eddng th\u1eb3ng) <br\/>V\u00ec ch\u1ec9 v\u1ebd \u0111\u01b0\u1ee3c 170 \u0111\u01b0\u1eddng th\u1eb3ng n\u00ean ta c\u00f3: <br\/> $\\begin{align*}190 - [\\dfrac{a. (a - 1)}{2} - 1] &= 170 \\\\ \\dfrac{a.(a - 1)}{2} - 1 &= 190 - 170 \\\\ \\dfrac{a.(a - 1)}{2} &= 20 + 1 \\\\ a . (a - 1) &= 21 . 2 \\\\ a . (a - 1) &= 42 \\\\ a . (a - 1) &= 7 . 6 \\end{align*}$ <br\/> $\\Rightarrow$ a = 7 hay c\u00f3 7 \u0111i\u1ec3m th\u1eb3ng h\u00e0ng <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 7 <\/span> "}]}],"id_ques":1948},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00fang hay sai","title_trans":"","temp":"true_false","correct":[["t","f","f","f"]],"list":[{"point":10,"image":"https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/bai3/lv3/img\/H613_K109.png","col_name":["Kh\u1eb3ng \u0111\u1ecbnh","\u0110\u00fang","Sai"],"arr_ques":[" Hai \u0111\u01b0\u1eddng th\u1eb3ng AB v\u00e0 BC tr\u00f9ng nhau"," Hai \u0111\u01b0\u1eddng th\u1eb3ng AB v\u00e0 BC ch\u1ec9 c\u00f3 1 \u0111i\u1ec3m chung"," Hai \u0111\u01b0\u1eddng th\u1eb3ng AB v\u00e0 AC l\u00e0 hai \u0111\u01b0\u1eddng th\u1eb3ng ph\u00e2n bi\u1ec7t ","Hai \u0111\u01b0\u1eddng th\u1eb3ng AB v\u00e0 AC song song v\u1edbi nhau"],"hint":"","explain":["\u0110\u00daNG - V\u00ec 3 \u0111i\u1ec3m A, B, C th\u1eb3ng h\u00e0ng n\u00ean AB, BC ch\u1ec9 l\u00e0 c\u00e1ch g\u1ecdi t\u00ean kh\u00e1c c\u1ee7a \u0111\u01b0\u1eddng th\u1eb3ng AC","SAI - V\u00ec hai \u0111\u01b0\u1eddng th\u1eb3ng AB v\u00e0 BC tr\u00f9ng nhau n\u00ean ch\u00fang c\u00f3 v\u00f4 s\u1ed1 \u0111i\u1ec3m chung ","SAI - V\u00ec AB v\u00e0 AC l\u00e0 hai \u0111\u01b0\u1eddng th\u1eb3ng tr\u00f9ng nhau","SAI - V\u00ec AB v\u00e0 AC l\u00e0 hai \u0111\u01b0\u1eddng th\u1eb3ng tr\u00f9ng nhau"]}]}],"id_ques":1949},{"time":24,"part":[{"title":"","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t ","select":["A. N\u1ebfu A $\\in$ m, B $\\in$ m v\u00e0 C $\\notin$ m th\u00ec 3 \u0111i\u1ec3m A, B, C th\u1eb3ng h\u00e0ng","B. N\u1ebfu A $\\in$ m, B $\\in$ m v\u00e0 C $\\in$ m th\u00ec 3 \u0111i\u1ec3m A, B, C th\u1eb3ng h\u00e0ng","C. N\u1ebfu A $\\notin$ m, B $\\notin$ m v\u00e0 C $\\notin$ m th\u00ec 3 \u0111i\u1ec3m A, B, C th\u1eb3ng h\u00e0ng"],"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> V\u1ebd h\u00ecnh minh h\u1ecda cho t\u1eebng \u0111\u00e1p \u00e1n r\u1ed3i ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> A. N\u1ebfu A $\\in$ m, B $\\in$ m v\u00e0 C $\\notin$ m ta c\u00f3 h\u00ecnh v\u1ebd: <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/bai3/lv3/img\/H613_K111.png' \/><\/center> <br\/>Quan s\u00e1t h\u00ecnh v\u1ebd ta th\u1ea5y A, B, C kh\u00f4ng th\u1eb3ng h\u00e0ng n\u00ean kh\u1eb3ng \u0111\u1ecbnh A, B, C th\u1eb3ng h\u00e0ng l\u00e0 <b> SAI <\/b> <br\/> B. N\u1ebfu A $\\in$ m, B $\\in$ m v\u00e0 C $\\in$ m ta c\u00f3 h\u00ecnh v\u1ebd: <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/bai3/lv3/img\/H613_K112.png' \/><\/center> <br\/> Quan s\u00e1t h\u00ecnh v\u1ebd ta th\u1ea5y 3 \u0111i\u1ec3m A, B, C th\u1eb3ng h\u00e0ng n\u00ean kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 <b> \u0110\u00daNG <\/b> <br\/> C. N\u1ebfu A $\\notin$ m, B $\\notin$ m v\u00e0 C $\\notin$ m ta c\u00f3 h\u00ecnh v\u1ebd: <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/hinhhoc/bai3/lv3/img\/H613_K113.png' \/><\/center> <br\/> Quan s\u00e1t h\u00ecnh v\u1ebd ta th\u1ea5y 3 \u0111i\u1ec3m , B, C kh\u00f4ng th\u1eb3ng h\u00e0ng n\u00ean kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 <b> SAI <\/b> <br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0: B <\/span> ","column":1}]}],"id_ques":1950}],"lesson":{"save":0,"level":3}}