{"id":7489,"date":"2021-11-20T13:53:54","date_gmt":"2021-11-20T06:53:54","guid":{"rendered":"https:\/\/www.vietlearn.org\/post\/?p=7489"},"modified":"2021-11-20T15:09:09","modified_gmt":"2021-11-20T08:09:09","slug":"vi-sao-co-the-tinh-nhanh-binh-phuong-cua-mot-so-hai-chu-so-co-chu-so-cuoi-la-5","status":"publish","type":"post","link":"https:\/\/www.vietlearn.org\/kien-thuc\/vi-sao-co-the-tinh-nhanh-binh-phuong-cua-mot-so-hai-chu-so-co-chu-so-cuoi-la-5\/","title":{"rendered":"V\u00ec sao c\u00f3 th\u1ec3 t\u00ednh nhanh b\u00ecnh ph\u01b0\u01a1ng c\u1ee7a m\u1ed9t s\u1ed1 hai ch\u1eef s\u1ed1 c\u00f3 ch\u1eef s\u1ed1 cu\u1ed1i l\u00e0 5?"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">B\u1ea1n c\u00f3 th\u1ec3 kh\u00f4ng c\u1ea7n d\u00f9ng b\u00fat t\u00ednh nhanh b\u00ecnh ph\u01b0\u01a1ng c\u1ee7a m\u1ed9t s\u1ed1 hai ch\u1eef s\u1ed1 c\u00f3 ch\u1eef s\u1ed1 cu\u1ed1i l\u00e0 5, v\u00ed d\u1ee5 35 \u0111\u01b0\u1ee3c kh\u00f4ng?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u00fang ta c\u00f3 th\u1ec3 d\u00f9ng c\u00e1c ki\u1ebfn th\u1ee9c \u0111\u1ea1i s\u1ed1 \u0111\u1ec3 ti\u1ebfn h\u00e0nh t\u00ednh nhanh b\u00ecnh ph\u01b0\u01a1ng c\u1ee7a c\u00e1c s\u1ed1 lo\u1ea1i n\u00e0y. \u0110\u1ec3 t\u00ednh b\u00ecnh ph\u01b0\u01a1ng m\u1ed9t s\u1ed1 hai ch\u1eef c\u00f3 ch\u1eef s\u1ed1 cu\u1ed1i l\u00e0 5 (ch\u1eef s\u1ed1 h\u00e0ng \u0111\u01a1n v\u1ecb l\u00e0 5), ta l\u1ea5y ch\u1eef s\u1ed1 h\u00e0ng ch\u1ee5c nh\u00e2n v\u1edbi ch\u1eef s\u1ed1 h\u00e0ng ch\u1ee5c c\u1ed9ng 1, vi\u1ebft ti\u1ebfp theo t\u00edch s\u1ed1 thu \u0111\u01b0\u1ee3c s\u1ed1 25, ta s\u1ebd c\u00f3 b\u00ecnh ph\u01b0\u01a1ng c\u1ea7n t\u00ednh. V\u00ed d\u1ee5 t\u00ednh b\u00ecnh ph\u01b0\u01a1ng c\u1ee7a s\u1ed1 35.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ta t\u00ednh t\u00edch s\u1ed1 (3 + 1) x 3 = 12. Vi\u1ebft s\u1ed1 12 b\u00ean tr\u00e1i s\u1ed1 25 ta c\u00f3 s\u1ed1 c\u1ea7n t\u00ecm l\u00e0 1225.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ta th\u1eed x\u00e9t quy t\u1eafc t\u00ednh n\u00e0y c\u00f3 \u0111\u00fang kh\u00f4ng?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ta vi\u1ebft con s\u1ed1 c\u1ea7n t\u00ednh d\u01b0\u1edbi d\u1ea1ng A = 10a + 5, a l\u00e0 con s\u1ed1 h\u00e0ng ch\u1ee5c. Theo c\u00f4ng th\u1ee9c (a + b)2 = a2 + 2ab + b2, ta c\u00f3: (10a + 5)2 = 100a2 + 2 x 5 x 10a + 25 = 100a2 + 100a + 25 = 100a (a + 1) + 25 = a(a + 1) x 100 + 25.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Nh\u01b0 v\u1eady l\u1ea5y a nh\u00e2n v\u1edbi a + 1 r\u1ed3i \u0111\u1eb7t t\u00edch s\u1ed1 thu \u0111\u01b0\u1ee3c b\u00ean tr\u00e1i s\u1ed1 25 l\u00e0 thu \u0111\u01b0\u1ee3c s\u1ed1 b\u00ecnh ph\u01b0\u01a1ng c\u1ea7n t\u00ednh, \u0111\u00f3 ch\u00ednh l\u00e0 quy t\u1eafc v\u1eeba \u0111\u1ec1 ra \u1edf tr\u00ean.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">T\u1eeb kho\u00e1: V\u1ec1 c\u00e1ch t\u00ednh nhanh.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"<p>B\u1ea1n c\u00f3 th\u1ec3 kh\u00f4ng c\u1ea7n d\u00f9ng b\u00fat t\u00ednh nhanh b\u00ecnh ph\u01b0\u01a1ng c\u1ee7a m\u1ed9t s\u1ed1 hai ch\u1eef s\u1ed1 c\u00f3 ch\u1eef s\u1ed1 cu\u1ed1i l\u00e0 5, v\u00ed d\u1ee5 35 \u0111\u01b0\u1ee3c kh\u00f4ng? Ch\u00fang ta c\u00f3 th\u1ec3 d\u00f9ng c\u00e1c ki\u1ebfn th\u1ee9c \u0111\u1ea1i s\u1ed1 \u0111\u1ec3 ti\u1ebfn h\u00e0nh t\u00ednh nhanh b\u00ecnh ph\u01b0\u01a1ng c\u1ee7a c\u00e1c s\u1ed1 lo\u1ea1i n\u00e0y. \u0110\u1ec3 t\u00ednh b\u00ecnh ph\u01b0\u01a1ng m\u1ed9t [&hellip;]<\/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-7489","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\/7489","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=7489"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7489\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=7489"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=7489"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=7489"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}