{"segment":[{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":10,"ques":" - (a - b - c) + (b - c + d) - (-a + b + d) = <span class='basic_hoi_black'>?<\/span>","select":["A. b","B. 3b + 2c + 2d","C. -b - 2c","D. -b"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u (-) \u0111\u1eb1ng tr\u01b0\u1edbc, ta ph\u1ea3i \u0111\u1ed5i t\u1ea5t c\u1ea3 c\u00e1c s\u1ed1 h\u1ea1ng trong d\u1ea5u ngo\u1eb7c: d\u1ea5u ( + ) th\u00e0nh d\u1ea5u ( - ) v\u00e0 d\u1ea5u ( - ) th\u00e0nh d\u1ea5u ( + )<br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u ( + ) \u0111\u1eb1ng tr\u01b0\u1edbc th\u00ec d\u1ea5u c\u00e1c s\u1ed1 h\u1ea1ng trong ngo\u1eb7c v\u1eabn gi\u1eef nguy\u00ean.<\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3:<br\/> $\\begin{align*} &- (a - b - c) + (b - c + d) - (-a + b + d) \\\\&= -a + b + c + b - c + d + a - b - d\\\\&= (a - a) + (b - b) + (c - c) + (d - d) + b\\\\&= 0 + 0 + 0 + 0 + b\\\\&= b\\end{align*}$<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n: <span class='basic_pink'> A. b<\/span><\/span> <br\/>","column":2}]}],"id_ques":5788},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":10,"ques":" T\u00ecm x, bi\u1ebft:<br\/>3 - (17 - x) = 289 - (36 + 289)","select":["A. x = -22","B. x = 22","C. x = 556","D. x = -556"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <br\/>B\u01b0\u1edbc 1: T\u00ednh v\u1ebf ph\u1ea3i<br\/>B\u01b0\u1edbc 2: T\u00ecm 17 - x<br\/>B\u01b0\u1edbc 3: T\u00ecm x<br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3:<br\/>$\\begin{align*}3 - (17 - x) &=289 - (36 + 289)\\\\3 - (17 - x)&= 289 - 36 - 289 \\\\3 - (17 - x)&=289 - 289 - 36\\\\3 - (17 - x)&= 0 - 36\\\\3 - (17 - x)&= -36\\\\17 - x&= 3 - (-36)\\\\17 - x&= 3 + 36\\\\17 - x&= 39\\\\x&= 17 - 39\\\\x&= 17 + (-39)\\\\x&= -22\\end{align*}$<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'> A. x = -22<\/span><\/span> <br\/>","column":2}]}],"id_ques":5789},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["-2"]]],"list":[{"point":10,"width":60,"type_input":"","ques":"B\u1ecf ngo\u1eb7c r\u1ed3i t\u00ednh: <br\/>-35 - [-(-38 + 55) - (48 - 32)] = _input_","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> + Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u (-) \u0111\u1eb1ng tr\u01b0\u1edbc, ta ph\u1ea3i \u0111\u1ed5i t\u1ea5t c\u1ea3 c\u00e1c s\u1ed1 h\u1ea1ng trong d\u1ea5u ngo\u1eb7c: d\u1ea5u ( + ) th\u00e0nh d\u1ea5u ( - ) v\u00e0 d\u1ea5u ( - ) th\u00e0nh d\u1ea5u ( + )<br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u ( + ) \u0111\u1eb1ng tr\u01b0\u1edbc th\u00ec d\u1ea5u c\u00e1c s\u1ed1 h\u1ea1ng trong ngo\u1eb7c v\u1eabn gi\u1eef nguy\u00ean<br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>$\\begin{align*}-35 - [-(-38 + 55) - (48 - 32)] &= -35 - (38 - 55 - 48 + 32)\\\\&= -35 - 38 + 55 + 48 - 32\\\\&= (55 - 35) + (48 - 38) -32\\\\&= 20 + 10 - 32\\\\&= 30 - 32\\\\&= 30 + (-32)\\\\&= -2 \\end{align*}$<br\/>V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0: <span class='basic_pink'> -2<\/span><br\/><b>Nh\u1eadn x\u00e9t:<\/b> B\u1ecf ngo\u1eb7c theo th\u1ee9 t\u1ef1 l\u00e0: ( ) $\\rightarrow$ [ ] $\\rightarrow$ { }<\/span> <\/span> <br\/>"}]}],"id_ques":5790},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["-42"]]],"list":[{"point":10,"width":60,"type_input":"","ques":"B\u1ecf ngo\u1eb7c r\u1ed3i t\u00ednh: <br\/>-(125 - 37) + [-28 - (31 - 105)] = _input_","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> + Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u (-) \u0111\u1eb1ng tr\u01b0\u1edbc, ta ph\u1ea3i \u0111\u1ed5i t\u1ea5t c\u1ea3 c\u00e1c s\u1ed1 h\u1ea1ng trong d\u1ea5u ngo\u1eb7c: d\u1ea5u ( + ) th\u00e0nh d\u1ea5u ( - ) v\u00e0 d\u1ea5u ( - ) th\u00e0nh d\u1ea5u ( + )<br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u ( + ) \u0111\u1eb1ng tr\u01b0\u1edbc th\u00ec d\u1ea5u c\u00e1c s\u1ed1 h\u1ea1ng trong ngo\u1eb7c v\u1eabn gi\u1eef nguy\u00ean<br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>$\\begin{align*}-(125 - 37) + [-28 - (31 - 105)] &= -125 + 37 + (-28 - 31 + 105) \\\\&= -125 + 37 - 28 - 31 + 105\\\\&= (-125 + 105) +(37 - 31) -28\\\\&= -20 + 6 - 28\\\\&= -14 - 28\\\\&= - (14 + 28)\\\\&= -42 \\end{align*}$<br\/>V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0: <span class='basic_pink'> -42<\/span><br\/><b>Nh\u1eadn x\u00e9t:<\/b> B\u1ecf ngo\u1eb7c theo th\u1ee9 t\u1ef1 l\u00e0: ( ) $\\rightarrow$ [ ] $\\rightarrow$ { }<\/span> <\/span> <br\/>"}]}],"id_ques":5791},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["-300","- 300"]]],"list":[{"point":10,"width":60,"type_input":"","ques":" T\u00ednh nhanh: <br\/>(73 - 651) - (192 - 551) + (27 - 108) = _input_","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u1ecf ngo\u1eb7c r\u1ed3i nh\u00f3m c\u1eb7p s\u1ed1 c\u00f3 t\u1ed5ng ho\u1eb7c hi\u1ec7u b\u1eb1ng 0 hay l\u00e0 s\u1ed1 tr\u00f2n ch\u1ee5c, tr\u00f2n tr\u0103m, tr\u00f2n ngh\u00ecn... \u0111\u1ec3 th\u1ef1c hi\u1ec7n t\u00ednh nhanh.<br\/><b>L\u01b0u \u00fd: <\/b><br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u (-) \u0111\u1eb1ng tr\u01b0\u1edbc, ta ph\u1ea3i \u0111\u1ed5i t\u1ea5t c\u1ea3 c\u00e1c s\u1ed1 h\u1ea1ng trong d\u1ea5u ngo\u1eb7c: d\u1ea5u ( + ) th\u00e0nh d\u1ea5u ( - ) v\u00e0 d\u1ea5u ( - ) th\u00e0nh d\u1ea5u ( + )<br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u ( + ) \u0111\u1eb1ng tr\u01b0\u1edbc th\u00ec d\u1ea5u c\u00e1c s\u1ed1 h\u1ea1ng trong ngo\u1eb7c v\u1eabn gi\u1eef nguy\u00ean.<\/span> <br\/><br\/><span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>$\\begin{align*}(73 - 651) - (192 - 551) + (27 - 108) &= 73 - 651 - 192 + 551 + 27 - 108 \\\\&= (73 + 27) - (651 - 551) - (192 + 108)\\\\&= 100 - 100 - 300\\\\&= 0 - 300\\\\&= -300\\end{align*}$<br\/>V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0: <span class='basic_pink'> -300<\/span><\/span> <br\/> <span class='basic_left'><span class='basic_green'>Nh\u1eadn x\u00e9t:<\/span> <br\/>Trong m\u1ed9t t\u1ed5ng \u0111\u1ea1i s\u1ed1, ta c\u00f3 th\u1ec3: \u0111\u1eb7t d\u1ea5u ngo\u1eb7c \u0111\u1ec3 nh\u00f3m c\u00e1c s\u1ed1 h\u1ea1ng m\u1ed9t c\u00e1ch t\u00f9y \u00fd v\u1edbi ch\u00fa \u00fd r\u1eb1ng n\u1ebfu tr\u01b0\u1edbc d\u1ea5u ngo\u1eb7c l\u00e0 d\u1ea5u ( - ) th\u00ec ph\u1ea3i \u0111\u1ed1i d\u1ea5u t\u1ea5t c\u1ea3 c\u00e1c s\u1ed1 h\u1ea1ng trong ngo\u1eb7c<br\/><b>V\u00ed d\u1ee5: a - b - c = a - (b + c)<\/b><\/span><\/span> "}]}],"id_ques":5792},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":10,"ques":" Cho P = (116 + 124) + (215 - 116 - 124)<br\/>Q = (435 + 167 - 89) - (435 - 89)<br\/>","select":["A. P > Q","B. P < Q","C. P = Q"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1: T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a P v\u00e0 Q<br\/>B\u01b0\u1edbc 2: So s\u00e1nh hai gi\u00e1 tr\u1ecb v\u1eeba t\u00ecm \u0111\u01b0\u1ee3c<br\/><b>L\u01b0u \u00fd: <\/b><br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u (-) \u0111\u1eb1ng tr\u01b0\u1edbc, ta ph\u1ea3i \u0111\u1ed5i t\u1ea5t c\u1ea3 c\u00e1c s\u1ed1 h\u1ea1ng trong d\u1ea5u ngo\u1eb7c: d\u1ea5u ( + ) th\u00e0nh d\u1ea5u ( - ) v\u00e0 d\u1ea5u ( - ) th\u00e0nh d\u1ea5u ( + )<br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u ( + ) \u0111\u1eb1ng tr\u01b0\u1edbc th\u00ec d\u1ea5u c\u00e1c s\u1ed1 h\u1ea1ng trong ngo\u1eb7c v\u1eabn gi\u1eef nguy\u00ean.<span class='basic_left'><\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>$\\begin{align*}P &= (116 + 124) + (215 - 116 - 124)\\\\&= 116 + 124 + 215 - 116 - 124 \\\\&= 215 + (116 - 116) + (124 - 124)\\\\&= 215 + 0 + 0\\\\&= 215\\end{align*}$<br\/>$\\begin{align*}Q &= (435 + 167 - 89) - (435 - 89)\\\\&= 435 + 167 - 89 - 435 + 89 \\\\&= 167 + (435 - 435) + (89 - 89)\\\\&= 169 + 0 + 0\\\\&= 169\\end{align*}$<br\/>M\u00e0<b> 215 > 167<\/b><br\/>$\\Rightarrow$ P > Q<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'> A. P > Q<\/span><\/span> <br\/><\/span>","column":3}]}],"id_ques":5793},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":" Cho P = a + (a + 3) - [(a + 2) - (a - 2)]<br\/>Q = a - [(a - 3) - (a + 3 + a + 2)]<br\/>","select":["A. P > Q","B. P < Q","C. P = Q"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1: T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a P v\u00e0 Q<br\/>B\u01b0\u1edbc 2: So s\u00e1nh hai gi\u00e1 tr\u1ecb v\u1eeba t\u00ecm \u0111\u01b0\u1ee3c<br\/><b>L\u01b0u \u00fd: <\/b><br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u (-) \u0111\u1eb1ng tr\u01b0\u1edbc, ta ph\u1ea3i \u0111\u1ed5i t\u1ea5t c\u1ea3 c\u00e1c s\u1ed1 h\u1ea1ng trong d\u1ea5u ngo\u1eb7c: d\u1ea5u ( + ) th\u00e0nh d\u1ea5u ( - ) v\u00e0 d\u1ea5u ( - ) th\u00e0nh d\u1ea5u ( + )<br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u ( + ) \u0111\u1eb1ng tr\u01b0\u1edbc th\u00ec d\u1ea5u c\u00e1c s\u1ed1 h\u1ea1ng trong ngo\u1eb7c v\u1eabn gi\u1eef nguy\u00ean.<span class='basic_left'><\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>$\\begin{align*}P &= a + (a + 3) - [(a + 2) - (a - 2)]\\\\&= a + a + 3 - (a + 2 - a + 2) \\\\&= 2a + 3 - [(a - a) + (2 + 2)]\\\\&= 2a + 3 - (0 + 4)\\\\&= 2a + 3 - 4\\\\&= 2a - (4 - 3)\\\\&= 2a - 1\\end{align*}$<br\/>$\\begin{align*}Q &= a - [(a - 3) - (a + 3 + a + 2)]\\\\&= a - (a - 3 - a - 3 - a - 2) \\\\&= a - a + 3 + a + 3 + a + 2\\\\&= (a - a) + (3 + 3 + 2) + (a + a)\\\\&= 0 + 8 + 2a\\\\&= 2a + 8\\end{align*}$<br\/>M\u00e0<b> 2a + 1 < 2a + 8<\/b><br\/>$\\Rightarrow$ P < Q<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'> B. P < Q<\/span><\/span> <br\/><\/span>","column":3}]}],"id_ques":5794},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["6"],["4"]]],"list":[{"point":10,"width":60,"type_input":"","ques":" Trong cu\u1ed9c thi ' H\u00e0nh tr\u00ecnh v\u0103n h\u1ecdc ' m\u1ed7i ng\u01b0\u1eddi tham d\u1ef1 \u0111\u01b0\u1ee3c t\u1eb7ng tr\u01b0\u1edbc 1000 \u0111i\u1ec3m. Sau \u0111\u00f3 m\u1ed7i c\u00e2u tr\u1ea3 l\u1eddi \u0111\u00fang \u0111\u01b0\u1ee3c 300 \u0111i\u1ec3m, m\u1ed7i c\u00e2u tr\u1ea3 l\u1eddi sai tr\u1eeb 150 \u0111i\u1ec3m. Sau 10 c\u00e2u h\u1ecfi ch\u1ecb Lan \u0111\u01b0\u1ee3c 2200 \u0111i\u1ec3m. V\u1eady ch\u1ecb Lan tr\u1ea3 l\u1eddi \u0111\u00fang _input_ c\u00e2u, sai _input_ c\u00e2u.","hint":"","explain":"<span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>G\u1ecdi s\u1ed1 c\u00e2u ch\u1ecb Lan tr\u1ea3 l\u1eddi \u0111\u00fang v\u00e0 sai l\u1ea7n l\u01b0\u1ee3t l\u00e0: a, b (c\u00e2u), ( a, b $\\in$N, a < 10, b < 10)<br\/>Theo \u0111\u1ec1 b\u00e0i ta c\u00f3:<br\/>1000 + 300.a - 150.b = 2200 <br\/>a + b = 10 <br\/>Ta c\u00f3 b\u1ea3ng gi\u00e1 tr\u1ecb nh\u01b0 sau:<br\/><table><tr><th>a<\/th><th>0<\/th><th>1<\/th><th>2<\/th><th>3<\/th><th>4<\/th><th>5<\/th><th>6<\/th><th>7<\/th><th>8<\/th><th>9<\/th><th>10<\/th><\/tr><tr><td>b<\/td><td>10<\/td><td>9<\/td><td>8<\/td><td>7<\/td><td>6<\/td><td>5<\/td><td>4<\/td><td>3<\/td><td>2<\/td><td>1<\/td><td>0<\/td><\/tr><tr><td>1000 + 300.a - 150.b<\/td><td>-500 (lo\u1ea1i)<\/td><td>-950 (lo\u1ea1i)<\/td><td>400 (lo\u1ea1i)<\/td><td>850 (lo\u1ea1i)<\/td><td>1300 (lo\u1ea1i)<\/td><td>1750 (lo\u1ea1i)<\/td><td>2200 (nh\u1eadn)<\/td><td>2650 (lo\u1ea1i)<\/td><td>3100 (lo\u1ea1i)<\/td><td>3550 (lo\u1ea1i)<\/td><td>4000 (lo\u1ea1i)<\/td><\/tr><\/table><br\/>$\\Rightarrow$ a = 6, b = 4<br\/>T\u1ee9c l\u00e0 ch\u1ecb Lan tr\u1ea3 l\u1eddi \u0111\u00fang 6 c\u00e2u, tr\u1ea3 l\u1eddi sai 4 c\u00e2u<br\/>V\u1eady c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u1ea7n l\u01b0\u1ee3t t\u1eeb tr\u00e1i qua ph\u1ea3i l\u00e0: <span class='basic_pink'>6; 4<\/span><\/span> <br\/><\/span>"}]}],"id_ques":5795},{"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":" -1 -2 - 3 - 4 - ... - 98 - 99 = <span class='basic_hoi_black'>?<\/span>","select":["A. 2400","B. 0","C. 4950","D. -4950"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>B\u01b0\u1edbc 1: \u0110\u01b0a v\u1ec1 d\u1ea1ng t\u1ed5ng \u0111\u1ec3 t\u00ednh<br\/>B\u01b0\u1edbc 2: Nh\u00f3m c\u00e1c c\u1eb7p c\u00f3 t\u1ed5ng b\u1eb1ng 0, s\u1ed1 tr\u00f2n ch\u1ee5c, tr\u00f2n tr\u0103m... \u0111\u1ec3 th\u1ef1c hi\u1ec7n t\u00ednh nhanh.<br\/><span class='basic_left'><\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>$\\begin{align*}&-1 -2 - 3 - 4 - ... - 98 - 99\\\\&= - (1 + 2 + 3 + 4 + ... + 96 + 97 + 98 + 99) \\\\&= - [(1 + 99) + (2 + 98) + (3 + 97) + (4 + 96) + ... + (49 + 51) + 50]\\\\&= - ( 100 + 100 + 100 + 100 + ... + 100 + 50) \\\\&= - ( 100 . 49 + 50)\\\\&= - (4900 + 50)\\\\&= -4950\\end{align*}$<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'> D. -4950<\/span><\/span> <br\/><br\/><span class='basic_left'><span class='basic_green'>Nh\u1eadn x\u00e9t:<\/span><br\/> + Khi \u0111\u1eb7t d\u1ea5u ngo\u1eb7c \u0111\u1ec3 nh\u00f3m c\u00e1c s\u1ed1 h\u1ea1ng n\u1ebfu tr\u01b0\u1edbc d\u1ea5u ngo\u1eb7c l\u00e0 d\u1ea5u ( - ) th\u00ec ph\u1ea3i \u0111\u1ed5i d\u1ea5u t\u1ea5t c\u1ea3 c\u00e1c s\u1ed1 h\u1ea1ng trong ngo\u1eb7c<br\/>V\u00ed d\u1ee5: <b>-a - b - c - d = - (a + b + c + d)<\/b><br\/>+ S\u1ed1 s\u1ed1 h\u1ea1ng c\u1ee7a d\u00e3y s\u1ed1 li\u00ean ti\u1ebfp t\u1eeb 1 \u0111\u1ebfn 99 l\u00e0: (99 - 1) : 1 + 1 = 99 s\u1ed1<br\/>V\u00ec th\u1ebf d\u00e3y s\u1ed1 t\u1eeb 1 \u0111\u1ebfn 99 tr\u1eeb s\u1ed1 50 ra th\u00ec nh\u00f3m \u0111\u01b0\u1ee3c: (99 - 1) : 2 = 49 (c\u1eb7p)<br\/>Do \u0111\u00f3 \u1edf b\u01b0\u1edbc 4 ph\u1ea7n b\u00e0i gi\u1ea3i c\u00f3 49 s\u1ed1 100<\/span><\/span>","column":2}]}],"id_ques":5796},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":" T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c: <br\/>B = x + y + z - y - (x - z) t\u1ea1i x = 38; y = -24; z = -35","select":["B = 0","B = -70","B = 6","B = 146"],"hint":" ","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>B\u01b0\u1edbc 1: Thay gi\u00e1 tr\u1ecb x = 38; y = -24; z = -35 v\u00e0o bi\u1ec3u th\u1ee9c B<br\/>B\u01b0\u1edbc 2: T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c<br\/><b>L\u01b0u \u00fd: <\/b><br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u (-) \u0111\u1eb1ng tr\u01b0\u1edbc, ta ph\u1ea3i \u0111\u1ed5i t\u1ea5t c\u1ea3 c\u00e1c s\u1ed1 h\u1ea1ng trong d\u1ea5u ngo\u1eb7c: d\u1ea5u ( + ) th\u00e0nh d\u1ea5u ( - ) v\u00e0 d\u1ea5u ( - ) th\u00e0nh d\u1ea5u ( + )<br\/>+ Khi b\u1ecf d\u1ea5u ngo\u1eb7c c\u00f3 d\u1ea5u ( + ) \u0111\u1eb1ng tr\u01b0\u1edbc th\u00ec d\u1ea5u c\u00e1c s\u1ed1 h\u1ea1ng trong ngo\u1eb7c v\u1eabn gi\u1eef nguy\u00ean.<span class='basic_left'><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Thay x = 38; y = -24; z = -35 v\u00e0o bi\u1ec3u th\u1ee9c B ta \u0111\u01b0\u1ee3c:<br\/> $\\begin{align*}B & =38 + (-24) + (-35) - (-24) - [38 - (-35)]\\\\&= 38 - 24 - 35 + 24 - (38 + 35) \\\\&= 38 - 24 - 35 + 24 - 38 - 35\\\\&= (38 - 38) + (24 - 24) - (35 + 35) \\\\&= 0 + 0 - 70\\\\&= -70\\end{align*}$<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'> B = -70<\/span><\/span> <br\/><\/span>","column":2}]}],"id_ques":5797}],"lesson":{"save":0,"level":3}}