\u1ede m\u1ed9t s\u1ed1 n\u01b0\u1edbc c\u00f3 n\u1ec1n y h\u1ecdc ti\u00ean ti\u1ebfn th\u01b0\u1eddng c\u00f3 vi\u1ec7c ki\u1ec3m tra \u0111\u1ecbnh k\u00ec m\u1ed9t s\u1ed1 b\u1ec7nh x\u00e3 h\u1ed9i. M\u1ed9t ph\u01b0\u01a1ng ph\u00e1p ki\u1ec3m tra b\u1ec7nh th\u00f4ng th\u01b0\u1eddng l\u00e0 ph\u01b0\u01a1ng ph\u00e1p th\u1eed m\u00e1u. Th\u00f4ng qua vi\u1ec7c th\u1eed m\u00e1u c\u00f3 th\u1ec3 ph\u00e1t hi\u1ec7n s\u1edbm c\u00e1c lo\u1ea1i b\u1ec7nh vi\u00eam gan, t\u1ea3, nhi\u1ec5m tr\u00f9ng m\u00e1u v\u00e0 nhi\u1ec1u b\u1ec7nh kh\u00e1c, nh\u1edd \u0111\u00f3 c\u00f3 th\u1ec3 ch\u1ea9n \u0111o\u00e1n v\u00e0 ch\u1eefa tr\u1ecb b\u1ec7nh s\u1edbm.<\/p>\n\n\n\n
Ph\u01b0\u01a1ng ph\u00e1p th\u1ef1c hi\u1ec7n ki\u1ec3m tra th\u01b0\u1eddng l\u00e0: C\u00e1c nh\u00e2n vi\u00ean y t\u1ebf \u0111\u1ebfn c\u00e1c \u0111i\u1ec3m ki\u1ec3m tra g\u1ecdi m\u1ed7i ng\u01b0\u1eddi l\u1ea5y m\u1ed9t \u00edt m\u00e1u, ghi phi\u1ebfu, nh\u00e2n vi\u00ean y t\u1ebf \u0111em v\u1ec1 c\u01a1 quan ki\u1ec3m tra, nghi\u00ean c\u1ee9u, cu\u1ed1i c\u00f9ng th\u00f4ng b\u00e1o k\u1ebft qu\u1ea3 ki\u1ec3m tra cho t\u1eebng ng\u01b0\u1eddi \u0111\u01b0\u1ee3c ki\u1ec3m tra. Ph\u01b0\u01a1ng ph\u00e1p ki\u1ec3m tra n\u00e0y c\u00f3 hi\u1ec7u qu\u1ea3, tuy nhi\u00ean qu\u00e1 tr\u00ecnh ki\u1ec3m tra kh\u00e1 t\u1ed1n c\u00f4ng s\u1ee9c.<\/p>\n\n\n\n
Li\u1ec7u c\u00f3 ph\u01b0\u01a1ng ph\u00e1p n\u00e0o ti\u1ebft ki\u1ec7m \u0111\u01b0\u1ee3c s\u1ee9c l\u1ef1c hay kh\u00f4ng? C\u00e2u tr\u1ea3 l\u1eddi l\u00e0 c\u00f3. Ch\u00fang ta n\u00eau l\u00ean m\u1ed9t v\u00ed d\u1ee5 \u0111\u1ec3 thuy\u1ebft minh v\u1ea5n \u0111\u1ec1 n\u00e0y.<\/p>\n\n\n\n
\u1ede m\u1ed9t th\u00e0nh ph\u1ed1 l\u1edbn n\u1ecd ng\u01b0\u1eddi ta l\u1ea5y \u0111\u01b0\u1ee3c m\u1ed9t s\u1ed1 l\u01b0\u1ee3ng l\u1edbn m\u1eabu m\u00e1u trong m\u1ed9t cu\u1ed9c ki\u1ec3m tra \u0111\u1ecbnh k\u00ec. \u0110\u1ec3 x\u1eed l\u00ed s\u1ed1 l\u01b0\u1ee3ng m\u1eabu m\u00e1u r\u1ea5t l\u1edbn n\u00e0y c\u00f3 th\u1ec3 c\u00f3 hai ph\u01b0\u01a1ng \u00e1n: Ph\u01b0\u01a1ng \u00e1n th\u00f4ng th\u01b0\u1eddng l\u00e0 ti\u1ebfn h\u00e0nh nghi\u00ean c\u1ee9u t\u1eebng m\u1eabu m\u00e1u. Ph\u01b0\u01a1ng \u00e1n kh\u00e1c chia c\u00e1c m\u1eabu m\u00e1u th\u00e0nh t\u1eebng nh\u00f3m, m\u1ed7i nh\u00f3m 100 m\u1eabu. Sau \u0111\u00f3 t\u1eeb m\u1ed7i nh\u00f3m l\u1ea5y m\u1ed7i m\u1eabu m\u1ed9t l\u01b0\u1ee3ng nh\u1ecf m\u00e1u (s\u1ed1 l\u01b0\u1ee3ng m\u00e1u \u00edt) \u0111em tr\u1ed9n l\u1eabn v\u1edbi nhau, sao \u0111\u00f3 ti\u1ebfn h\u00e0nh ki\u1ec3m tra h\u1ed7n h\u1ee3p m\u00e1u \u0111\u00e3 tr\u1ed9n. N\u1ebfu k\u1ebft qu\u1ea3 ki\u1ec3m tra trong m\u1eabu h\u1ed7n h\u1ee3p n\u00e0y l\u00e0 \u00e2m t\u00ednh, ch\u1ee9ng t\u1ecf \u1edf 100 m\u1eabu m\u00e1u v\u1eeba x\u00e9t l\u00e0 kh\u00f4ng c\u00f3 m\u1ea7m b\u1ec7nh. N\u1ebfu k\u1ebft qu\u1ea3 ki\u1ec3m tra m\u1eabu m\u00e1u h\u1ed7n h\u1ee3p l\u00e0 d\u01b0\u01a1ng t\u00ednh (v\u00ed d\u1ee5 b\u1ec7nh vi\u00eam gan) th\u00ec trong nh\u00f3m m\u00e1u \u0111\u00e3 ch\u1ecdn m\u1eabu h\u1ed7n h\u1ee3p \u00edt nh\u1ea5t c\u00f3 m\u1ed9t m\u1eabu m\u00e1u c\u00f3 m\u1ea7m b\u1ec7nh. \u0110\u1ec3 ki\u1ec3m tra m\u1eabu m\u00e1u n\u00e0o c\u00f3 m\u1ea7m b\u1ec7nh trong 100 m\u1eabu m\u00e1u n\u00e0y ph\u1ea3i ti\u1ebfn h\u00e0nh ki\u1ec3m tra c\u1ee5 th\u1ec3 t\u1eebng m\u1eabu m\u00e1u trong nh\u00f3m n\u00e0y. Th\u1ebf d\u00f9ng ph\u01b0\u01a1ng \u00e1n ki\u1ec3m tra n\u00e0o th\u00ec t\u1ed1t h\u01a1n?<\/p>\n\n\n\n
N\u1ebfu d\u00f9ng ph\u01b0\u01a1ng \u00e1n th\u1ee9 nh\u1ea5t, ph\u1ea3i th\u1ef1c hi\u1ec7n 100 l\u1ea7n ki\u1ec3m tra cho m\u1ed7i nh\u00f3m m\u1eabu m\u00e1u; n\u1ebfu d\u00f9ng ph\u01b0\u01a1ng \u00e1n hai th\u00ec c\u00f3 kh\u1ea3 n\u0103ng ch\u1ec9 ti\u1ebfn h\u00e0nh m\u1ed9t l\u1ea7n ki\u1ec3m tra, ho\u1eb7c c\u00f3 th\u1ec3 c\u00f3 kh\u1ea3 n\u0103ng ph\u1ea3i l\u00e0m 101 l\u1ea7n ki\u1ec3m tra. \u0110\u1ec3 l\u00e0m ph\u00e9p so s\u00e1nh, c\u1ea7n ph\u1ea3i xem x\u00e9t s\u1ed1 l\u1ea7n trung b\u00ecnh c\u1ea7n ti\u1ebfn h\u00e0nh ki\u1ec3m tra cho m\u1ed7i nh\u00f3m m\u1eabu m\u00e1u, nh\u1edd \u0111\u00f3 m\u00e0 trong hai lo\u1ea1i ph\u01b0\u01a1ng \u00e1n th\u00ec ph\u01b0\u01a1ng \u00e1n n\u00e0o ph\u1ea3i th\u1ef1c hi\u1ec7n s\u1ed1 l\u1ea7n ki\u1ec3m tra nhi\u1ec1u h\u01a1n v\u00e0 nhi\u1ec1u h\u01a1n bao nhi\u00eau l\u1ea7n?<\/p>\n\n\n\n
D\u1ef1a v\u00e0o s\u1ed1 li\u1ec7u ki\u1ec3m tra s\u01a1 b\u1ed9 tr\u01b0\u1edbc \u0111\u00f3 (tr\u01b0\u1edbc khi l\u00e0m ki\u1ec3m tra \u0111\u1ea1i tr\u00e0 ph\u1ea3i l\u00e0m th\u00ed nghi\u1ec7m ki\u1ec3m tra cho m\u1ed9t ph\u1ea1m vi nh\u1ecf) v\u00e0 nh\u1eadn \u0111\u01b0\u1ee3c t\u1ec9 l\u1ec7 vi\u00eam gan trung b\u00ecnh l\u00e0 0,1%, t\u1ee9c c\u1ee9 1000 ng\u01b0\u1eddi c\u00f3 m\u1ed9t ng\u01b0\u1eddi b\u1ecb l\u00e2y nhi\u1ec5m b\u1ec7nh vi\u00eam gan, ho\u1eb7c c\u00f3 th\u1ec3 n\u00f3i \u1edf m\u1ed7i nh\u00f3m m\u1eabu m\u00e1u kh\u1ea3 n\u0103ng c\u00f3 0,1% s\u1ed1 m\u1eabu m\u00e1u c\u00f3 b\u1ec7nh vi\u00eam gan. V\u00ec v\u1eady \u1edf m\u1ed7i nh\u00f3m 100 m\u1eabu m\u00e1u kh\u1ea3 n\u0103ng \u0111\u1ec3 m\u1ed9t m\u1eabu m\u00e1u kh\u00f4ng mang b\u1ec7nh l\u00e0: (1 – 0,1%)100 \u2248 90,48%. v\u00e0 kh\u1ea3 n\u0103ng c\u00f3 m\u1eabu m\u00e1u mang b\u1ec7nh l\u00e0 1- 90,48% = 9,52%.<\/p>\n\n\n\n
V\u00ec v\u1eady n\u1ebfu d\u00f9ng ph\u01b0\u01a1ng \u00e1n ki\u1ec3m tra hai th\u00ec s\u1ed1 l\u1ea7n trung b\u00ecnh c\u1ea7n th\u1ef1c hi\u1ec7n cho m\u1ed9t nh\u00f3m m\u00e1u l\u00e0: 1 x 90,48% + 101 x 9,52% = 10,52 l\u1ea7n.<\/p>\n\n\n\n
So v\u1edbi ph\u01b0\u01a1ng \u00e1n \u0111\u1ea7u th\u00ec ti\u1ebft ki\u1ec7m \u0111\u01b0\u1ee3c 89,48%. N\u1ebfu m\u1ed7i l\u1ea7n th\u1eed m\u00e1u c\u1ea7n 10.000 \u0111 th\u00ec \u0111\u1ec3 th\u1eed m\u1ed9t tri\u1ec7u m\u1eabu m\u00e1u theo ph\u01b0\u01a1ng \u00e1n m\u1ed9t ph\u1ea3i t\u1ed1n \u0111\u1ebfn 1,4 t\u1ec9 \u0111\u1ed3ng, trong khi d\u00f9ng ph\u01b0\u01a1ng \u00e1n hai ch\u1ec9 t\u1ed1n 1.472.800 \u0111, nh\u01b0 v\u1eady so v\u1edbi ph\u01b0\u01a1ng \u00e1n m\u1ed9t th\u00ec ti\u1ebft ki\u1ec7m \u0111\u1ebfn h\u01a1n 10 tri\u1ec7u \u0111\u1ed3ng.<\/p>\n\n\n\n
Trong th\u1ef1c t\u1ebf, khi x\u00e9t nghi\u1ec7m m\u00e1u theo ph\u01b0\u01a1ng \u00e1n hai kh\u00f4ng nh\u1ea5t thi\u1ebft ph\u00e2n chia th\u00e0nh nh\u00f3m 100 m\u1eabu m\u00e1u, m\u00e0 c\u00f3 th\u1ec3 chia th\u00e0nh nh\u00f3m, m\u1ed7i nh\u00f3m c\u00f3 50 m\u1eabu, 150 m\u1eabu tu\u1ef3 s\u1ed1 l\u01b0\u1ee3ng m\u1eabu m\u00e1u \u0111\u00e3 thu th\u1eadp \u0111\u01b0\u1ee3c. C\u00e1c b\u1ea1n th\u1eed t\u00ednh xem so v\u1edbi ph\u01b0\u01a1ng \u00e1n m\u1ed9t th\u00ec ph\u01b0\u01a1ng \u00e1n hai ti\u1ebft ki\u1ec7m \u0111\u01b0\u1ee3c bao nhi\u00eau n\u1ebfu s\u1ed1 m\u1eabu m\u00e1u l\u00e0 10.000 m\u1eabu.<\/p>\n\n\n\n
L\u00e0m th\u1ebf n\u00e0o \u0111\u1ec3 t\u00ednh s\u1ed1 l\u01b0\u1ee3t tr\u1eadn \u0111\u1ea5u cho th\u1ec3 th\u1ee9c thi \u0111\u1ea5u lo\u1ea1i tr\u1ef1c ti\u1ebfp?<\/p>\n\n\n\n
Gi\u1ea3 s\u1eed \u1edf tr\u01b0\u1eddng b\u1ea1n \u0111ang t\u1ed5 ch\u1ee9c m\u1ed9t cu\u1ed9c thi \u0111\u1ea5u c\u1edd theo th\u1ec3 l\u1ec7 \u0111\u1ea5u lo\u1ea1i tr\u1ef1c ti\u1ebfp, v\u00ed d\u1ee5 s\u1ed1 ng\u01b0\u1eddi ghi t\u00ean thi \u0111\u1ea5u l\u00e0 50, b\u1ea1n c\u00f3 th\u1ec3 t\u00ednh \u0111\u01b0\u1ee3c s\u1ed1 tr\u1eadn \u0111\u1ea5u \u0111\u1ec3 d\u1ef1a v\u00e0o \u0111\u00f3 b\u1ed1 tr\u00ed l\u1ecbch thi \u0111\u1ea5u, s\u1ed1 \u0111\u1ea5u tr\u01b0\u1eddng. N\u1ebfu b\u1ea1n \u0111\u01b0\u1ee3c giao t\u1ed5 ch\u1ee9c cu\u1ed9c thi \u0111\u1ea5u, b\u1ea1n c\u00f3 t\u00ednh \u0111\u01b0\u1ee3c kh\u00f4ng?<\/p>\n\n\n\n
B\u1edfi v\u00ec tr\u1eadn \u0111\u1ea5u chung k\u1ebft ch\u1ec9 x\u1ea3y ra gi\u1eefa hai ng\u01b0\u1eddi cu\u1ed1i c\u00f9ng, hai ng\u01b0\u1eddi n\u00e0y l\u1ea1i ch\u1ecdn t\u1eeb 22 = 4 ng\u01b0\u1eddi trong tr\u1eadn \u0111\u1ea5u tr\u01b0\u1edbc \u0111\u00f3, m\u00e0 b\u1ed1n ng\u01b0\u1eddi n\u00e0y l\u1ea1i \u0111\u01b0\u1ee3c ch\u1ecdn tr\u1ef1c ti\u1ebfp t\u1eeb 33 = 8 ng\u01b0\u1eddi trong cu\u1ed9c \u0111\u1ea5u tr\u01b0\u1edbc \u0111\u00f3\u2026 N\u1ebfu s\u1ed1 ng\u01b0\u1eddi ghi t\u00ean \u0111\u00fang b\u1eb1ng c\u00e1c lu\u1ef9 th\u1eeba c\u1ee7a 2 nh\u01b0 2, 4 (22), 8 (23), 16 (24), 32 (25)\u2026th\u00ec ch\u1ec9 c\u1ea7n theo s\u1ed1 ng\u01b0\u1eddi ghi t\u00ean th\u00e0nh nh\u00f3m ti\u1ebfn h\u00e0nh thi \u0111\u1ea5u cho t\u1eebng nh\u00f3m, sau \u0111\u00f3 lo\u1ea1i d\u1ea7n t\u1eebng b\u01b0\u1edbc l\u00e0 \u0111\u01b0\u1ee3c. Gi\u1ea3 s\u1eed s\u1ed1 ng\u01b0\u1eddi ghi t\u00ean kh\u00f4ng \u0111\u00fang b\u1eb1ng lu\u1ef9 th\u1eeba nguy\u00ean c\u1ee7a 2 th\u00ec trong thi \u0111\u1ea5u c\u00f3 v\u00f2ng \u0111\u01b0\u1ee3c mi\u1ec5n. N\u1ebfu ta x\u1ebfp 2 ng\u01b0\u1eddi m\u1ed9t thi \u0111\u1ea5u ngay t\u1eeb \u0111\u1ea7u th\u00ec s\u1ebd c\u00f3 m\u1ed9t s\u1ed1 v\u00f2ng \u0111\u01b0\u1ee3c mi\u1ec5n thi \u0111\u1ea5u \u1edf giai \u0111o\u1ea1n gi\u1eefa ho\u1eb7c giai \u0111o\u1ea1n cu\u1ed1i, m\u00e0 c\u00e1c tr\u1eadn \u0111\u1ea5u \u1edf giai \u0111o\u1ea1n n\u00e0y th\u01b0\u1eddng kh\u00e1 c\u0103ng th\u1eb3ng v\u00ec c\u00e1c \u0111\u1ea5u th\u1ee7 ng\u00e0y c\u00e0ng m\u1ea1nh, c\u01a1 h\u1ed9i \u0111\u01b0\u1ee3c mi\u1ec5n hay kh\u00f4ng, r\u00f5 r\u00e0ng kh\u00f4ng b\u00ecnh \u0111\u1eb3ng. \u0110\u1ec3 cho c\u01a1 h\u1ed9i t\u01b0\u01a1ng \u0111\u1ed1i \u0111\u1ed3ng \u0111\u1ec1u khi\u1ebfn thi \u0111\u1ea5u ng\u00e0y c\u00e0ng s\u00f4i n\u1ed5i, n\u00f3i chung ng\u01b0\u1eddi ta th\u01b0\u1eddng mi\u1ec5n thi \u0111\u1ea5u \u1edf v\u00f2ng m\u1ed9t. V\u00ec 50 l\u00e0 trung gian gi\u1eefa 32 (25) v\u00e0 64 (26) m\u00e0 50 – 32 = 18 n\u00ean v\u00f2ng \u0111\u1ea7u c\u1ea7n lo\u1ea1i 18 \u0111\u1ea5u th\u1ee7, t\u1ee9c c\u1ea7n ti\u1ebfn h\u00e0nh thi \u0111\u1ea5u 18 tr\u1eadn \u0111\u1ea5u cho v\u00f2ng \u0111\u1ea7u t\u1ee9c c\u00f3 36 ng\u01b0\u1eddi tham gia thi \u0111\u1ea5u v\u00e0 14 ng\u01b0\u1eddi mi\u1ec5n thi \u0111\u1ea5u. Sau lo\u1ea1t tr\u1eadn thi \u0111\u1ea5u \u1edf v\u00f2ng m\u1ed9t s\u1ebd lo\u1ea1i 18 \u0111\u1ea5u th\u1ee7 v\u00e0 c\u00f2n l\u1ea1i 32 ng\u01b0\u1eddi. T\u1eeb v\u00f2ng \u0111\u1ea5u th\u1ee9 hai s\u1ebd kh\u00f4ng c\u00f2n tr\u01b0\u1eddng h\u1ee3p mi\u1ec5n thi \u0111\u1ea5u n\u1eefa. V\u00e0 \u1edf v\u00f2ng hai s\u1ebd c\u00f3 16 tr\u1eadn \u0111\u1ea5u, v\u00f2ng th\u1ee9 ba c\u00f3 8 tr\u1eadn \u0111\u1ea5u, v\u00f2ng \u0111\u1ea5u th\u1ee9 t\u01b0 c\u00f3 b\u1ed1n tr\u1eadn \u0111\u1ea5u, v\u00f2ng \u0111\u1ea5u th\u1ee9 n\u0103m s\u1ebd c\u00f3 hai tr\u1eadn \u0111\u1ea5u. V\u00f2ng \u0111\u1ea5u th\u1ee9 s\u00e1u s\u1ebd l\u00e0 tr\u1eadn chung k\u1ebft \u0111\u1ec3 gi\u00e0nh ch\u1ee9c v\u00f4 \u0111\u1ecbch. V\u1eady t\u1ed5ng c\u1ed9ng s\u1ed1 c\u00e1c tr\u1eadn \u0111\u1ea5u s\u1ebd l\u00e0 18 + 16 + 8 + 4 + 2 + 1 = 49 tr\u1eadn so v\u1edbi s\u1ed1 \u0111\u1ea5u th\u1ee7 50 th\u00ec nh\u1ecf h\u01a1n 1.<\/p>\n\n\n\n
Ta l\u1ea1i x\u00e9t v\u00ed d\u1ee5 v\u1ec1 tr\u1eadn thi \u0111\u1ea5u qu\u1ed1c t\u1ebf v\u1ec1 b\u00f3ng \u0111\u00e1 n\u0103m 1998 \u1edf Ph\u00e1p, t\u1ed5ng s\u1ed1 c\u00f3 32 \u0111\u1ed9i b\u00f3ng \u0111\u00e1 tham gia v\u00f2ng chung k\u1ebft gi\u1ea3i b\u00f3ng \u0111\u00e1 th\u1ebf gi\u1edbi n\u0103m 1998. Ph\u01b0\u01a1ng th\u1ee9c thi \u0111\u1ea5u \u1edf v\u00f2ng chung k\u1ebft chia l\u00e0m hai giai \u0111o\u1ea1n. Giai \u0111o\u1ea1n \u0111\u1ea7u chia b\u1ea3ng, \u0111\u1ea5u v\u00f2ng tr\u00f2n t\u00ednh \u0111i\u1ec3m, sau \u0111\u00f3 theo th\u1ec3 th\u1ee9c \u0111\u1ea5u lo\u1ea1i tr\u1ef1c ti\u1ebfp. N\u1ebfu ti\u1ebfn h\u00e0nh thi \u0111\u1ea5u theo th\u1ec3 th\u1ee9c \u0111\u1ea5u lo\u1ea1i tr\u1ef1c ti\u1ebfp ngay t\u1eeb v\u00f2ng \u0111\u1ea7u th\u00ec ph\u1ea3i x\u1ebfp bao nhi\u00eau tr\u1eadn \u0111\u1ea5u? V\u00ec 32 ch\u00ednh b\u1eb1ng 25 n\u00ean t\u1ed5ng s\u1ed1 c\u00e1c tr\u1eadn \u0111\u1ea5u theo th\u1ec3 th\u1ee9c \u0111\u1ea5u lo\u1ea1i tr\u1ef1c ti\u1ebfp s\u1ebd l\u00e0 16 + 8 + 4 + 2 + 1 = 31 tr\u1eadn, \u00edt h\u01a1n s\u1ed1 \u0111\u1ed9i tham gia l\u00e0 1.<\/p>\n\n\n\n
B\u00e2y gi\u1edd ta x\u00e9t tr\u01b0\u1eddng h\u1ee3p chung c\u00f3 M ng\u01b0\u1eddi tham gia thi \u0111\u1ea5u. Gi\u1ea3 s\u1eed M l\u1edbn h\u01a1n 2n v\u00e0 nh\u1ecf h\u01a1n 2n+1, th\u1ebf th\u00ec c\u1ea7n n + 1 v\u00f2ng thi \u0111\u1ea5u, trong \u0111\u00f3 s\u1ed1 v\u00f2ng thi \u0111\u1ea5u \u0111\u1ea7u ti\u00ean s\u1ebd l\u00e0 M – 2n. Sau v\u00f2ng \u0111\u1ea7u, s\u1ed1 ng\u01b0\u1eddi c\u00f2n ch\u01b0a thi \u0111\u1ea5u s\u1ebd l\u00e0 M -(m – 2n) = 2n. Trong n v\u00f2ng thi \u0111\u1ea5u ti\u1ebfp sau, t\u1ed5ng s\u1ed1 c\u00e1c tr\u1eadn thi \u0111\u1ea5u s\u1ebd l\u00e0: 2n-1 +2n-2 + 2n-3 +\u2026+23 + 22 + 2 + 1 = (2n-1 +2n-2 + 2n-3 +\u2026+23 + 22 + 2) + 1 x (2 – 1) = (2n + 2n-1 + 2n-2 + \u2026 +23 + 22 + 2) – (2n-1 + 2n-2 + 2n-3 +\u2026+23 + 22 + 2 + 1) = 2n-1<\/p>\n\n\n\n
V\u00e0 t\u1ed5ng s\u1ed1 c\u00e1c tr\u1eadn thi \u0111\u1ea5u s\u1ebd l\u00e0: (M – 2n) + 2n -1 = M – 1<\/p>\n\n\n\n
Ngh\u0129a l\u00e0 \u00edt h\u01a1n s\u1ed1 \u0111\u1ed9i tham gia l\u00e0 1.<\/p>\n\n\n\n
Th\u1ef1c ra, trong m\u1ed7i tr\u1eadn thi \u0111\u1ea5u s\u1ebd lo\u1ea1i b\u1ecf m\u1ed9t \u0111\u1ea5u th\u1ee7. Trong M ng\u01b0\u1eddi tham gia thi \u0111\u1ea5u s\u1ebd ch\u1ecdn \u0111\u01b0\u1ee3c 1 v\u00f4 \u0111\u1ecbch v\u00e0 lo\u1ea1i b\u1ecf M – 1 \u0111\u1ea5u th\u1ee7 v\u00ec v\u1eady s\u1ed1 tr\u1eadn thi \u0111\u1ea5u l\u00e0 M – 1. B\u1ea1n h\u00e3y theo c\u00e1ch tr\u00ecnh b\u00e0y, t\u00ednh s\u1ed1 tr\u1eadn thi \u0111\u1ea5u b\u00f3ng b\u00e0n c\u00f3 158 \u0111\u1ea5u th\u1ee7 nam v\u00e0 96 \u0111\u1ea5u th\u1ee7 n\u1eef tham gia.<\/p>\n\n\n\n
T\u1eeb kho\u00e1: Th\u1ec3 th\u1ee9c \u0111\u1ea5u lo\u1ea1i.<\/p>\n\n\n\n
<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"
\u1ede m\u1ed9t s\u1ed1 n\u01b0\u1edbc c\u00f3 n\u1ec1n y h\u1ecdc ti\u00ean ti\u1ebfn th\u01b0\u1eddng c\u00f3 vi\u1ec7c ki\u1ec3m tra \u0111\u1ecbnh k\u00ec m\u1ed9t s\u1ed1 b\u1ec7nh x\u00e3 h\u1ed9i. M\u1ed9t ph\u01b0\u01a1ng ph\u00e1p ki\u1ec3m tra b\u1ec7nh th\u00f4ng th\u01b0\u1eddng l\u00e0 ph\u01b0\u01a1ng ph\u00e1p th\u1eed m\u00e1u. Th\u00f4ng qua vi\u1ec7c th\u1eed m\u00e1u c\u00f3 th\u1ec3 ph\u00e1t hi\u1ec7n s\u1edbm c\u00e1c lo\u1ea1i b\u1ec7nh vi\u00eam gan, t\u1ea3, nhi\u1ec5m tr\u00f9ng m\u00e1u v\u00e0 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_disable_autopaging":false},"categories":[15,9],"tags":[],"class_list":["post-7593","post","type-post","status-publish","format-standard","hentry","category-hoi-dap-khoa-hoc","category-toan-hoc"],"_links":{"self":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7593","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/comments?post=7593"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7593\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=7593"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=7593"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=7593"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}