Ng\u01b0\u1eddi \u0111\u1eddi sau g\u1ecdi lo\u1ea1i b\u00e0i to\u00e1n n\u00e0y l\u00e0 \u201cB\u00e0i to\u00e1n g\u00e0 th\u1ecf chung l\u1ed3ng\u201d. N\u1ebfu b\u00e2y gi\u1edd d\u00f9ng ki\u1ebfn th\u1ee9c gi\u1ea3i h\u1ec7 ph\u01b0\u01a1ng tr\u00ecnh th\u00ec vi\u1ec7c gi\u1ea3i b\u00e0i to\u00e1n l\u00e0 kh\u00e1 d\u1ec5 d\u00e0ng. N\u1ebfu g\u1ecdi x l\u00e0 s\u1ed1 g\u00e0 v\u00e0 y l\u00e0 s\u1ed1 th\u1ecf, d\u1ef1a theo \u0111\u1ec1 to\u00e1n ta vi\u1ebft h\u1ec7 ph\u01b0\u01a1ng tr\u00ecnh x + y = 35 2x + 4y = 94<\/p>\n\n\n\n
Gi\u1ea3i h\u1ec7 ph\u01b0\u01a1ng tr\u00ecnh hai \u1ea9n s\u1ed1 ta d\u1ec5 d\u00e0ng t\u00ecm th\u1ea5y x = 23, y = 12.<\/p>\n\n\n\n
Trong \u201cS\u00e1ch to\u00e1n T\u00f4n t\u1eed\u201d ng\u01b0\u1eddi ta \u0111\u00e3 s\u1eed d\u1ee5ng l\u00ed lu\u1eadn sau \u0111\u00e2y \u0111\u1ec3 \u0111\u01b0a ra l\u1eddi gi\u1ea3i: M\u1ed9t n\u1eeda s\u1ed1 ch\u00e2n tr\u1eeb \u0111i s\u1ed1 \u0111\u1ea7u s\u1ebd b\u1eb1ng s\u1ed1 th\u1ecf t\u1ee9c 94\/2- 35 = 12 th\u1ecf.<\/p>\n\n\n\n
L\u1ea5y s\u1ed1 \u0111\u1ea7u tr\u1eeb s\u1ed1 th\u1ecf s\u1ebd l\u00e0 s\u1ed1 g\u00e0: 35 -12 = 23. C\u00e1ch gi\u1ea3i t\u1ef1 nhi\u00ean v\u00e0 c\u0169ng h\u1ee3p l\u00f4gic.<\/p>\n\n\n\n
Trong s\u00e1ch kh\u00f4ng h\u1ec1 \u0111\u01b0a ra nguy\u00ean nh\u00e2n \u0111\u01b0a ra l\u1eddi gi\u1ea3i, nh\u01b0ng con \u0111\u01b0\u1eddng \u0111\u1ec3 \u0111\u01b0a ra l\u1eddi gi\u1ea3i c\u0169ng d\u1ec5 th\u1ea5y.<\/p>\n\n\n\n
V\u00ec g\u00e0 ch\u1ec9 c\u00f3 hai ch\u00e2n, th\u1ecf c\u00f3 b\u1ed1n ch\u00e2n, s\u1ed1 ch\u00e2n th\u1ecf g\u1ea5p \u0111\u00f4i s\u1ed1 ch\u00e2n g\u00e0. N\u1ebfu l\u1ea5y m\u1ed9t n\u1eeda s\u1ed1 ch\u00e2n tr\u1eeb \u0111i s\u1ed1 \u0111\u1ea7u (c\u1ee7a c\u1ea3 th\u1ecf v\u00e0 g\u00e0) ta th\u1ea5y \u0111\u01b0\u1ee3c s\u1ed1 \u0111\u1ea7u th\u1ecf v\u00e0 t\u1eeb \u0111\u00f3 d\u1ec5 d\u00e0ng t\u00ecm th\u1ea5y s\u1ed1 \u0111\u1ea7u g\u00e0 (t\u1ee9c s\u1ed1 g\u00e0 trong l\u1ed3ng). N\u1ebfu d\u00f9ng k\u00ed hi\u1ec7u thay th\u1ebf ta s\u1ebd d\u1ec5 d\u00e0ng th\u1ea5y r\u00f5 c\u00e1ch l\u1eadp lu\u1eadn v\u1eeba n\u00eau. N\u1ebfu g\u1ecdi x l\u00e0 s\u1ed1 g\u00e0, y l\u00e0 s\u1ed1 th\u1ecf th\u00ec 1\/2(2x + 4y) – (x + y) = y<\/p>\n\n\n\n
L\u1ea5y t\u1ed5ng s\u1ed1 th\u1ecf v\u00e0 g\u00e0 tr\u1eeb \u0111i s\u1ed1 th\u1ecf ta c\u00f3 (x + y) – y = x<\/p>\n\n\n\n
B\u00e0i to\u00e1n th\u1ecf – g\u00e0 v\u1ec1 sau xu\u1ea5t hi\u1ec7n nhi\u1ec1u ph\u01b0\u01a1ng \u00e1n, c\u00e1ch gi\u1ea3i c\u0169ng kh\u00e1c nhau. Ngo\u00e0i c\u00e1ch gi\u1ea3i tr\u00ean \u0111\u00e2y c\u00f3 th\u1ec3 c\u00f3 c\u00e1ch gi\u1ea3i kh\u00e1c. V\u00ed d\u1ee5 gi\u1ea3 thi\u1ebft to\u00e0n b\u1ed9 s\u1ed1 \u0111\u1ea7u trong l\u1ed3ng \u0111\u1ec1u l\u00e0 \u0111\u1ea7u th\u1ecf th\u00ec s\u1ed1 ch\u00e2n \u1eaft ph\u1ea3i c\u00f3 l\u00e0 g\u1ea5p b\u1ed1n l\u1ea7n s\u1ed1 \u0111\u1ea7u t\u1ee9c ph\u1ea3i c\u00f3 140 ch\u00e2n. Th\u1ef1c t\u1ebf l\u1ea1i ch\u1ec9 c\u00f3 94 ch\u00e2n n\u00ean s\u1ed1 ch\u00e2n th\u1eeba l\u00e0 46 do ng\u1ed9 nh\u1eadn g\u00e0 th\u00e0nh th\u1ecf, m\u00e0 g\u00e0 c\u00f3 hai ch\u00e2n, s\u1ed1 g\u00e0 ph\u1ea3i l\u00e0 m\u1ed9t n\u1eeda s\u1ed1 ch\u00e2n th\u1eeba v\u00e0 l\u00e0 23. V\u00e0 s\u1ed1 \u0111\u1ea7u th\u1ecf ph\u1ea3i l\u00e0 t\u1ed5ng s\u1ed1 \u0111\u1ea7u tr\u1eeb \u0111i s\u1ed1 \u0111\u1ea7u g\u00e0 t\u1ee9c s\u1ed1 \u0111\u1ea7u th\u1ecf l\u00e0 12.<\/p>\n\n\n\n
T\u1eeb kho\u00e1: B\u00e0i to\u00e1n g\u00e0 v\u00e0 th\u1ecf chung l\u1ed3ng.<\/p>\n\n\n\n
<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"
Ng\u01b0\u1eddi \u0111\u1eddi sau g\u1ecdi lo\u1ea1i b\u00e0i to\u00e1n n\u00e0y l\u00e0 \u201cB\u00e0i to\u00e1n g\u00e0 th\u1ecf chung l\u1ed3ng\u201d. N\u1ebfu b\u00e2y gi\u1edd d\u00f9ng ki\u1ebfn th\u1ee9c gi\u1ea3i h\u1ec7 ph\u01b0\u01a1ng tr\u00ecnh th\u00ec vi\u1ec7c gi\u1ea3i b\u00e0i to\u00e1n l\u00e0 kh\u00e1 d\u1ec5 d\u00e0ng. N\u1ebfu g\u1ecdi x l\u00e0 s\u1ed1 g\u00e0 v\u00e0 y l\u00e0 s\u1ed1 th\u1ecf, d\u1ef1a theo \u0111\u1ec1 to\u00e1n ta vi\u1ebft h\u1ec7 ph\u01b0\u01a1ng tr\u00ecnh x […]<\/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-7565","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\/7565","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=7565"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7565\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=7565"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=7565"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=7565"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}