{"segment":[{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["11"]]],"list":[{"point":10,"width":60,"content":"","type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/daiso/bai9/lv3/img\/11.jpg' \/><\/center> <br\/> T\u1ed5ng $\\overline{ab} + \\overline{ba}$ lu\u00f4n chia h\u1ebft cho: _input_ ","hint":"Vi\u1ebft $\\overline{ab}$ = 10 . a + b, t\u01b0\u01a1ng t\u1ef1 v\u1edbi $\\overline{ba}$","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> Vi\u1ebft $\\overline{ab}$ = 10 . a + b, t\u01b0\u01a1ng t\u1ef1 $\\overline{ba}$ = b . 10 + a <br\/> Bi\u1ebfn \u0111\u1ed5i t\u1ed5ng tr\u00ean th\u00e0nh t\u00edch c\u1ee7a m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean v\u00e0 \u1ea9n <br\/> S\u1ed1 \u0111\u00f3 ch\u00ednh l\u00e0 s\u1ed1 m\u00e0 t\u1ed5ng tr\u00ean lu\u00f4n chia h\u1ebft <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3: <br\/> $\\begin{align*} \\overline{ab} + \\overline{ba} &= a . 10 + b + b . 10 + a \\\\ &= (a. 10 + a) + (b . 10 + b) \\\\ &= 11 . a + 11 . b \\\\ &= 11. (a + b) \\end{align*}$ <br\/> V\u1eady t\u1ed5ng $\\overline{ab} + \\overline{ba}$ $\\vdots$ 11 <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 11 <\/span>"}]}],"id_ques":451},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["1"]]],"list":[{"point":10,"width":60,"content":"","type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/daiso/bai9/lv3/img\/4.jpg' \/><\/center> <br\/> Cho A = 9413 . 12 + 930 . 48 + 11 + x <br\/> T\u00ecm x nh\u1ecf nh\u1ea5t \u0111\u1ec3 A chia h\u1ebft cho 12 <br\/> V\u1eady x = _input_","hint":"N\u1ebfu m\u1ecdi s\u1ed1 h\u1ea1ng trong t\u1ed5ng \u0111\u1ec1u chia h\u1ebft cho m\u1ed9t s\u1ed1 th\u00ec t\u1ed5ng chia h\u1ebft cho s\u1ed1 \u0111\u00f3","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> N\u1ebfu m\u1ecdi s\u1ed1 h\u1ea1ng trong t\u1ed5ng \u0111\u1ec1u chia h\u1ebft cho m\u1ed9t s\u1ed1 th\u00ec t\u1ed5ng chia h\u1ebft cho s\u1ed1 \u0111\u00f3<\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3: <br\/> V\u00ec 12 $\\vdots$ 12 n\u00ean 9413 . 12 $\\vdots$ 12 <br\/> V\u00ec 48 $\\vdots$ 12 n\u00ean 930 . 48 $\\vdots$ 12 <br\/> \u0110\u1ec3 A $\\vdots$ 12 th\u00ec (11 + x) $\\vdots$ 12 <br\/> A nh\u1ecf nh\u1ea5t chia h\u1ebft cho 12 khi x = 1<br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 1 <\/span>"}]}],"id_ques":452},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["7"]]],"list":[{"point":10,"width":60,"content":"","type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/daiso/bai9/lv3/img\/4.jpg' \/><\/center> <br\/> Cho A = 30 . 11385 + 3 . 31754 . 5 + 23 + x <br\/> T\u00ecm x nh\u1ecf nh\u1ea5t \u0111\u1ec3 A chia h\u1ebft cho 15 <br\/> V\u1eady x = _input_","hint":"N\u1ebfu m\u1ecdi s\u1ed1 h\u1ea1ng trong t\u1ed5ng \u0111\u1ec1u chia h\u1ebft cho m\u1ed9t s\u1ed1 th\u00ec t\u1ed5ng chia h\u1ebft cho s\u1ed1 \u0111\u00f3","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> N\u1ebfu m\u1ecdi s\u1ed1 h\u1ea1ng trong t\u1ed5ng \u0111\u1ec1u chia h\u1ebft cho m\u1ed9t s\u1ed1 th\u00ec t\u1ed5ng chia h\u1ebft cho s\u1ed1 \u0111\u00f3 <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3: <br\/> V\u00ec 30 $\\vdots$ 15 n\u00ean 30 . 11385 $\\vdots$ 15 <br\/> V\u00ec 3 . 5 = 15 $\\vdots$ 15 n\u00ean 3 . 31754 . 5 $\\vdots$ 15 <br\/> \u0110\u1ec3 A $\\vdots$ 15 th\u00ec (23 + x) $\\vdots$ 15 <br\/> A nh\u1ecf nh\u1ea5t chia h\u1ebft cho 15 khi x = 7<br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 7 <\/span>"}]}],"id_ques":453},{"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":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/daiso/bai9/lv3/img\/2.jpg' \/><\/center> <br\/> Cho S = $1 + 2 + 2^2 + 2^3 + 2^4 + 2^5 + 2^6 + 2^7$ ","select":["A. S $\\vdots$ 2 ","B. S $\\vdots$ 8 ","C. S $\\vdots$ 3 ","D. S $\\vdots$ 6"],"hint":"N\u1ebfu m\u1ecdi s\u1ed1 h\u1ea1ng trong t\u1ed5ng \u0111\u1ec1u chia h\u1ebft cho m\u1ed9t s\u1ed1 th\u00ec t\u1ed5ng chia h\u1ebft cho s\u1ed1 \u0111\u00f3","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e9t t\u1eebng s\u1ed1 h\u1ea1ng trong t\u1ed5ng xem c\u00f3 chia h\u1ebft cho 2; 3; 6; 8 kh\u00f4ng <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> V\u00ec S =$1 + 2 + 2^2 + 2^3 + 2^4 + 2^5 + 2^6 + 2^7$ <br\/> $\\Rightarrow$ S $\\not \\vdots$ 2 n\u00ean S $\\not \\vdots$ 6, S $\\not \\vdots$ 8 <br\/> Ta c\u00f3: 1 + 2 = 3 $\\vdots$ 3 <br\/> $\\begin{cases}2^2 \\text{chia 3 d\u01b0 1} \\\\ 2^3 \\text{chia 3 d\u01b0 2} \\end{cases} \\Rightarrow (2^2 + 2^3) \\vdots 3 \\\\ \\begin{cases}2^4 \\text{chia 3 d\u01b0 1} \\\\ 2^5 \\text{chia 3 d\u01b0 2} \\end{cases} \\Rightarrow (2^4 + 2^5) \\vdots 3 \\\\ \\begin{cases}2^6 \\text{chia 3 d\u01b0 1} \\\\ 2^7 \\text{chia 3 d\u01b0 2} \\end{cases} \\Rightarrow (2^6 + 2^7) \\vdots 3$ <br\/> V\u1eady S $\\vdots$ 3 <br\/> <span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: C<\/span> ","column":2}]}],"id_ques":454},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":10,"ques":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/daiso/bai9/lv3/img\/10.jpg' \/><\/center> <br\/> Cho S = 1001 + 28 + 44 <br\/>Kh\u1eb3ng \u0111\u1ecbnh n\u00e0o sau \u0111\u00e2y \u0111\u00fang? ","select":["A. S $\\vdots$ 7 ","B. S $\\vdots$ 4 ","C. S $\\vdots$ 11","D. S $\\not \\vdots$ 7"],"hint":"N\u1ebfu m\u1ecdi s\u1ed1 h\u1ea1ng trong t\u1ed5ng \u0111\u1ec1u chia h\u1ebft cho m\u1ed9t s\u1ed1 th\u00ec t\u1ed5ng chia h\u1ebft cho s\u1ed1 \u0111\u00f3","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e9t t\u1eebng s\u1ed1 h\u1ea1ng trong t\u1ed5ng xem c\u00f3 chia h\u1ebft cho 7; 4 v\u00e0 11 kh\u00f4ng <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> 1001 $\\vdots$ 7 ; 28 $\\vdots$ 7 v\u00e0 44 $\\not \\vdots$ 7 <br\/> $\\Rightarrow$ (1001 + 28 + 44 ) $\\not \\vdots$ 7 <br\/> 1001 $\\not \\vdots$ 4; 28 $\\vdots$ 4; 44 $\\vdots$ 4 <br\/> $\\Rightarrow$ (1001 + 28 + 44) $\\not \\vdots$ 4 <br\/> 1001 $\\vdots$ 11; 28 $\\not \\vdots$ 11; 44 $\\vdots$ 11 <br\/> $\\Rightarrow$ (1001 + 28 + 44) $\\not \\vdots$ 11<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: D <\/span> ","column":2}]}],"id_ques":455},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["475"],["71"]]],"list":[{"point":10,"width":60,"content":"","type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/daiso/bai9/lv3/img\/7.jpg' \/><\/center> <br\/> T\u00ecm s\u1ed1 b\u1ecb chia v\u00e0 s\u1ed1 chia bi\u1ebft th\u01b0\u01a1ng l\u00e0 6, d\u01b0 l\u00e0 49. T\u1ed5ng c\u1ee7a s\u1ed1 b\u1ecb chia, s\u1ed1 chia v\u00e0 d\u01b0 b\u1eb1ng 595 <br\/> V\u1eady s\u1ed1 b\u1ecb chia l\u00e0: _input_<br\/> S\u1ed1 chia l\u00e0: _input_","hint":"S\u1ed1 b\u1ecb chia = th\u01b0\u01a1ng . s\u1ed1 chia + s\u1ed1 d\u01b0","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> S\u1ed1 b\u1ecb chia = th\u01b0\u01a1ng . s\u1ed1 chia + d\u01b0 <br\/> G\u1ecdi s\u1ed1 b\u1ecb chia l\u00e0 a, s\u1ed1 chia l\u00e0 b (a, b $\\in \\mathbb{N}$, b > 49) <br\/>Theo b\u00e0i ra ta c\u00f3: a = b . 6 + 49 v\u00e0 a + b + 49 = 595 <br\/> Bi\u1ebfn \u0111\u1ed5i 2 bi\u1ec3u th\u1ee9c tr\u00ean \u0111\u1ec3 t\u00ecm a v\u00e0 b<\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3: <br\/> G\u1ecdi s\u1ed1 b\u1ecb chia l\u00e0 a, s\u1ed1 chia l\u00e0 b (a, b $\\in \\mathbb{N}$ ) <br\/> V\u00ec th\u01b0\u01a1ng l\u00e0 6 v\u00e0 d\u01b0 b\u1eb1ng 49 n\u00ean ta c\u00f3 a = 6 . b + 49 (1) <br\/> Theo b\u00e0i ra t\u1ed5ng c\u1ee7a s\u1ed1 b\u1ecb chia, s\u1ed1 chia v\u00e0 d\u01b0 l\u00e0 595 <br\/> a + b + 49 = 595 n\u00ean a + b = 546 (2) <br\/> T\u1eeb (1) v\u00e0 (2) $\\Rightarrow$ (6 . b + 49) + b = 546 <br\/> 7 . b = 546 - 49 <br\/> 7. b = 497 <br\/> b = 71 <br\/> $\\Rightarrow$ a = 6 . 71 + 49 = 475 <br\/> V\u1eady s\u1ed1 b\u1ecb chia l\u00e0 475, s\u1ed1 chia l\u00e0 71 <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 475; 71 <\/span>"}]}],"id_ques":456},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["5"]]],"list":[{"point":10,"width":60,"content":"","type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/daiso/bai9/lv3/img\/11.jpg' \/><\/center> <br\/> T\u00ecm n \u0111\u1ec3 $(n^2 + 2n + 7)$ $\\vdots$ (n + 2) <br\/> V\u1eady n = _input_","hint":"Bi\u1ebfn \u0111\u1ed5i $(n^2 + 2n + 7)$ th\u00e0nh t\u1ed5ng ho\u1eb7c hi\u1ec7u c\u1ee7a m\u1ed9t s\u1ed1 chia h\u1ebft cho n + 2 v\u00e0 m\u1ed9t s\u1ed1","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> Bi\u1ebfn \u0111\u1ed5i $(n^2 + 2n + 7)$ = n. (n + 2) + b ( b $\\in \\mathbb{N}$) <br\/> Khi \u0111\u00f3 $(n^2 + 2n + 7)$ chia h\u1ebft cho (n + 2) khi b chia h\u1ebft cho (n + 2) <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3: <br\/> $(n^2 + 2n + 7) = n . (n + 2) + 7$ <br\/> V\u00ec n . (n + 2) $\\vdots$ (n + 2) n\u00ean \u0111\u1ec3 $(n^2 + 2n + 7)$ $\\vdots$ (n + 2) th\u00ec 7 $\\vdots$ (n + 2) <br\/> 7 ch\u1ec9 chia h\u1ebft cho 1 ho\u1eb7c 7 $\\Rightarrow$ n + 2 = 1 (kh\u00f4ng c\u00f3 gi\u00e1 tr\u1ecb n\u00e0o c\u1ee7a n th\u1ecfa m\u00e3n) <br\/> Ho\u1eb7c n + 2 = 7 $\\Rightarrow$ n = 5 <br\/> V\u1eady v\u1edbi n = 5 th\u00ec $(n^2 + 2n + 7)$ $\\vdots$ n + 2 <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 5 <\/span>"}]}],"id_ques":457},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["1"],["2"]]],"list":[{"point":10,"width":60,"content":"","type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/daiso/bai9/lv3/img\/11.jpg' \/><\/center> <br\/> T\u00ecm n \u0111\u1ec3 (4n - 5) $\\vdots$ (2n - 1) <br\/> V\u1eady n = _input_; _input_","hint":"Bi\u1ebfn \u0111\u1ed5i 4n - 5 th\u00e0nh d\u1ea1ng t\u1ed5ng ho\u1eb7c hi\u1ec7u c\u1ee7a m\u1ed9t s\u1ed1 chia h\u1ebft cho 2n - 1 v\u00e0 m\u1ed9t s\u1ed1","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> Bi\u1ebfn \u0111\u1ed5i 4n - 5 = 2 . (2n - 1) + a (a $\\in \\mathbb{N}$) <br\/> Khi \u0111\u00f3 4n - 5 chia h\u1ebft cho 2n - 1 khi a chia h\u1ebft cho 2n - 1 <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3: <br\/> 4n - 5 = 4n - (2 + 3) = 4n - 2 - 3 <br\/> V\u00ec (4n - 2) $\\vdots$ (2n - 1) <br\/> N\u00ean \u0111\u1ec3 (4n - 5) $\\vdots$ (2n - 1) th\u00ec 3 $\\vdots$ (2n - 1) <br\/> 3 ch\u1ec9 chia h\u1ebft cho 1 ho\u1eb7c 3 n\u00ean 2n - 1 = 1 $\\Rightarrow$ n = 1 <br\/> Ho\u1eb7c 2n - 1 = 3 $\\Rightarrow$ n = 2 <br\/> V\u1eady v\u1edbi n = 1 ho\u1eb7c n = 2 th\u00ec (4n - 5) $\\vdots$ (2n - 1) <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 1; 2 <\/span>"}]}],"id_ques":458},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["5"]]],"list":[{"point":10,"width":60,"content":"","type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/daiso/bai9/lv3/img\/6.jpg' \/><\/center> <br\/> T\u00ecm x bi\u1ebft $(x^3 - 3 . 5^2) : 2 - 1 = 2^3 . 3$ <br\/> V\u1eady x = _input_","hint":"T\u00ednh l\u0169y th\u1eeba tr\u01b0\u1edbc, bi\u1ebfn \u0111\u1ed5i \u0111\u01b0a v\u1ec1 d\u1ea1ng $x^3 = a^3$ ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> T\u00ednh c\u00e1c l\u0169y th\u1eeba tr\u01b0\u1edbc <br\/> \u0110\u01b0a VP v\u1ec1 d\u1ea1ng l\u0169y th\u1eeba b\u1eadc 3 <br\/> $a^m = b^m$ khi v\u00e0 ch\u1ec9 khi a = b <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3: <br\/> $\\begin{align*} (x^3 - 3 . 5^2) : 2 - 1 &= 2^3 . 3 \\\\ (x^3 - 3 . 25) : 2 - 1 &= 8 . 3 \\\\ (x^3 - 75) : 2 &= 24 + 1 \\\\ (x^3 - 75) &= 25 . 2 \\\\ (x^3 - 75) &= 50 \\\\ x^3 &= 50 + 75 \\\\ x^3 &= 125 \\\\ x^3 &= 5^3 \\end{align*}$ <br\/> V\u00ec $x^3 = 5^3$ khi x = 5 <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 5 <\/span>"}]}],"id_ques":459},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["8"],["2"]]],"list":[{"point":10,"width":60,"content":"","type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop6/toan/daiso/bai9/lv3/img\/1.png' \/><\/center> <br\/> T\u00ecm a, b bi\u1ebft a - b = 6 v\u00e0 $\\overline{4a7} + \\overline{1b5}$ chia h\u1ebft cho 9 <br\/> V\u1eady a = _input_; b = _input_ ","hint":"$\\overline{4a7} + \\overline{1b5}$ chia h\u1ebft cho 9 khi t\u1ed5ng c\u00e1c ch\u1eef s\u1ed1 chia h\u1ebft cho 9","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> Ta c\u00f3 a - b = 6 v\u00e0 $\\overline{4a7} + \\overline{1b5}$ chia h\u1ebft cho 9 <br\/> $\\overline{4a7} + \\overline{1b5}$ $\\vdots$ 9 khi t\u1ed5ng c\u00e1c ch\u1eef s\u1ed1 chia h\u1ebft cho 9 <br\/> D\u1ef1a v\u00e0o \u0111\u00f3 ta t\u00ecm a v\u00e0 b <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3: <br\/> $\\overline{4a7} + \\overline{1b5}$ chia h\u1ebft cho 9 khi t\u1ed5ng c\u00e1c ch\u1eef s\u1ed1 chia h\u1ebft cho 9 <br\/> $\\overline{4a7} + \\overline{1b5}$ = 400 + a . 10 + 7 + 100 + b . 10 + 5 = 512 + 10 . (a + b) chia h\u1ebft cho 9 <br\/> 512 + 10.(a + b) = 504 + 8 + 9.(a + b) + a + b <br\/> V\u00ec 504 $\\vdots$ 9; 9 . (a + b) $\\vdots$ 9 v\u00e0 8 chia 9 d\u01b0 8 n\u00ean t\u1ed5ng tr\u00ean chia h\u1ebft cho 9 khi (a + b) chia 9 d\u01b0 1 <br\/> N\u00ean a + b = 1 ho\u1eb7c a + b = 10 <br\/> V\u00ec a - b = 6 n\u00ean a + b = 10 <br\/> V\u1eady a = (10 + 6) : 2 = 8; b = 10 - 8 = 2 <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: a = 8, b = 2 <\/span>"}]}],"id_ques":460}],"lesson":{"save":0,"level":3}}