M\u1eddi c\u00e1c b\u1ea1n xem x\u00e9t nh\u00f3m s\u1ed1 d\u01b0\u1edbi \u0111\u00e2y: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233.<\/p>\n\n\n\n
D\u00e3y s\u1ed1 n\u00e0y \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 d\u00e3y s\u1ed1 Phib\u00f4naxi, m\u1ed7i con s\u1ed1 trong d\u00e3y s\u1ed1 \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 s\u1ed1 h\u1ea1ng Phib\u00f4naxi.<\/p>\n\n\n\n
Phib\u00f4naxi l\u00e0 nh\u00e0 to\u00e1n h\u1ecdc Italia, v\u00e0o th\u1eddi trung c\u1ed5. Sau khi \u0111i du l\u1ecbch \u1edf ph\u01b0\u01a1ng \u0110\u00f4ng \u00f4ng \u0111\u00e3 vi\u1ebft m\u1ed9t quy\u1ec3n s\u00e1ch to\u00e1n \u201cS\u00e1ch to\u00e1n ph\u00e1p\u201d. Trong s\u00e1ch c\u00f3 \u0111\u01b0a ra m\u1ed9t b\u00e0i to\u00e1n v\u1ec1 kh\u1ea3 n\u0103ng sinh \u0111\u1ebb c\u1ee7a m\u1ed9t \u0111\u00f4i th\u1ecf: N\u1ebfu m\u1ed7i \u0111\u00f4i th\u1ecf trong m\u1ed9t th\u00e1ng sinh \u0111\u01b0\u1ee3c m\u1ed9t \u0111\u00f4i th\u1ecf con, m\u00e0 m\u1ed7i \u0111\u00f4i th\u1ecf m\u1edbi sinh sau khi sinh \u0111\u01b0\u1ee3c ba th\u00e1ng s\u1ebd l\u1ea1i \u0111\u1ebb \u0111\u01b0\u1ee3c m\u1ed9t \u0111\u00f4i th\u1ecf m\u1edbi. Gi\u1ea3 s\u1eed kh\u00f4ng c\u00f3 t\u1eed vong c\u1ee7a th\u1ecf trong th\u1eddi gian \u0111ang x\u00e9t, nh\u01b0 v\u1eady m\u1ed9t \u0111\u00f4i th\u1ecf m\u1edbi sinh th\u00ec sau m\u1ed9t n\u0103m s\u1ea3n sinh \u0111\u01b0\u1ee3c bao nhi\u00eau \u0111\u00f4i th\u1ecf m\u1edbi?<\/p>\n\n\n\n
Gi\u1ea3 thi\u1ebft th\u00e1ng 12 n\u0103m tr\u01b0\u1edbc, \u0111\u00f4i th\u1ecf non ra \u0111\u1eddi. V\u00e0o th\u00e1ng 1 n\u0103m m\u1edbi v\u1eabn ch\u1ec9 c\u00f3 m\u1ed9t \u0111\u00f4i th\u1ecf. \u0110\u1ebfn th\u00e1ng 2, \u0111\u00f4i th\u1ecf n\u00e0y l\u1ea1i sinh m\u1ed9t \u0111\u00f4i th\u1ecf m\u1edbi, t\u1ed5ng c\u1ed9ng c\u00f3 hai \u0111\u00f4i. \u0110\u1ebfn th\u00e1ng 3, \u0111\u01b0\u01a1ng nhi\u00ean ch\u1ec9 c\u00f3 \u0111\u00f4i th\u1ecf sinh v\u00e0o th\u00e1ng 12 n\u0103m tr\u01b0\u1edbc sinh m\u1ed9t \u0111\u00f4i th\u1ecf m\u1edbi, n\u00ean t\u1ed5ng c\u1ed9ng v\u00e0o th\u00e1ng 3 ta c\u00f3 ba \u0111\u00f4i th\u1ecf. \u0110\u1ebfn th\u00e1ng 4, \u0111\u00f4i th\u1ecf \u1edf \u0111\u1ed9 tu\u1ed5i hai th\u00e1ng s\u1ebd sinh m\u1ed9t \u0111\u00f4i th\u1ecf m\u1edbi, v\u00ec v\u1eady c\u00f3 hai \u0111\u00f4i th\u1ecf m\u1edbi sinh, th\u00eam v\u00e0o ba \u0111\u00f4i th\u1ecf \u0111\u00e3 c\u00f3 n\u00ean v\u00e0o l\u00fac n\u00e0y ta c\u00f3 t\u1ea5t c\u1ea3 l\u00e0 n\u0103m \u0111\u00f4i th\u1ecf. \u0110\u1ebfn th\u00e1ng 5 l\u1ea1i c\u00f3 \u0111\u00f4i th\u1ecf sinh v\u00e0o th\u00e1ng 3 l\u1ea1i sinh m\u1ed9t \u0111\u00f4i th\u1ecf m\u1edbi, n\u00ean c\u00f3 ba \u0111\u00f4i th\u1ecf m\u1edbi sinh th\u00eam v\u00e0o n\u0103m \u0111\u00f4i th\u1ecf v\u1ed1n c\u00f3, v\u1eady v\u00e0o th\u00e1ng 5 ta c\u00f3 t\u1ea5t c\u1ea3 l\u00e0 t\u00e1m \u0111\u00f4i th\u1ecf. C\u1ee9 suy lu\u1eadn t\u00ednh to\u00e1n li\u00ean ti\u1ebfp nh\u01b0 \u0111\u00e3 tr\u00ecnh b\u00e0y \u1edf tr\u00ean, ta s\u1ebd c\u00f3 s\u1ed1 c\u00e1c \u0111\u00f4i th\u1ecf m\u1edbi sinh s\u1ebd theo \u0111\u00fang d\u00e3y s\u1ed1 Phib\u00f4naxi v\u00e0 \u1edf s\u1ed1 h\u1ea1ng th\u1ee9 13, s\u1ed1 \u0111\u00f4i th\u1ecf s\u1ebd l\u00e0 233 \u0111\u00f4i. Nh\u01b0 v\u1eady ta \u0111\u00e3 t\u00ecm \u0111\u01b0\u1ee3c l\u1eddi gi\u1ea3i cho b\u00e0i to\u00e1n \u0111\u00e3 n\u00eau tr\u00ean.<\/p>\n\n\n\n
Nghi\u00ean c\u1ee9u d\u00e3y s\u1ed1 ta s\u1ebd t\u00ecm th\u1ea5y quy lu\u1eadt t\u1ea1o n\u00ean d\u00e3y s\u1ed1: Con s\u1ed1 \u0111\u1ee9ng sau b\u1eb1ng t\u1ed5ng hai s\u1ed1 li\u00ean ti\u1ebfp tr\u01b0\u1edbc \u0111\u00f3. D\u00f9ng ph\u01b0\u01a1ng ph\u00e1p quy n\u1ea1p to\u00e1n h\u1ecdc ta c\u00f3 th\u1ec3 t\u00ednh \u0111\u01b0\u1ee3c s\u1ed1 h\u1ea1ng th\u1ee9 (m + n) c\u1ee7a d\u00e3y s\u1ed1 theo c\u00f4ng th\u1ee9c am+n = am-1.an + am.an+1<\/p>\n\n\n\n
D\u00f9ng quy t\u1eafc n\u00e0y ta c\u00f3 th\u1ec3 t\u00ednh s\u1ed1 h\u1ea1ng b\u1ea5t k\u00ec c\u1ee7a d\u00e3y s\u1ed1 Phib\u00f4naxi. V\u00ed d\u1ee5 khi c\u1ea7n t\u00ednh s\u1ed1 h\u1ea1ng th\u1ee9 25 l\u00e0 a25. Ta \u0111\u1eb7t m = 13, n = 12. T\u1eeb \u0111\u00f3 ta c\u00f3: a13+2 = a13.1.a12 + a13.a12+1 = = 1442 + 2332 = 75025<\/p>\n\n\n\n
B\u1ea1n h\u00e3y th\u1eed t\u00ednh s\u1ed1 h\u1ea1ng a24<\/p>\n\n\n\n
T\u1eeb kho\u00e1: D\u00e3y s\u1ed1 Phib\u00f4naxi; S\u1ed1 h\u1ea1ng Phib\u00f4naxi.<\/p>\n\n\n\n
<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"
M\u1eddi c\u00e1c b\u1ea1n xem x\u00e9t nh\u00f3m s\u1ed1 d\u01b0\u1edbi \u0111\u00e2y: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. D\u00e3y s\u1ed1 n\u00e0y \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 d\u00e3y s\u1ed1 Phib\u00f4naxi, m\u1ed7i con s\u1ed1 trong d\u00e3y s\u1ed1 \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 s\u1ed1 h\u1ea1ng Phib\u00f4naxi. Phib\u00f4naxi l\u00e0 nh\u00e0 to\u00e1n h\u1ecdc Italia, v\u00e0o th\u1eddi trung c\u1ed5. Sau khi […]<\/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-7581","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\/7581","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=7581"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7581\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=7581"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=7581"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=7581"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}