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1/
$M=\frac{1}{3.8}+\frac{1}{8.13}+\frac{1}{13.18}+....+\frac{1}{33.38}$
$5M=\frac{8-3}{3.8}+\frac{13-8}{8.13}+\frac{18-13}{13.18}+...+\frac{38-33}{33.38}$
$=\frac{1}{3}-\frac{1}{8}+\frac{1}{8}-\frac{1}{13}+\frac{1}{13}-\frac{1}{18}+....+\frac{1}{33}-\frac{1}{38}$
$=\frac{1}{3}-\frac{1}{38}=\frac{35}{114}$
$\Rightarrow M=\frac{35}{114}:5=\frac{7}{114}$
2/
$N=\frac{1}{3.10}+\frac{1}{10.17}+\frac{1}{17.24}+\frac{1}{24.31}+\frac{1}{31.38}$
$7N=\frac{10-3}{3.10}+\frac{17-10}{10.17}+\frac{24-17}{17.24}+\frac{31-24}{24.31}+\frac{38-31}{31.38}$
$=\frac{1}{3}-\frac{1}{10}+\frac{1}{10}-\frac{1}{17}+\frac{1}{17}-\frac{1}{24}+\frac{1}{24}-\frac{1}{31}+\frac{1}{31}-\frac{1}{38}$
$=\frac{1}{3}-\frac{1}{38}=\frac{35}{114}$
$\Rightarrow N=\frac{35}{114}:7=\frac{5}{114}$
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107-{38+[7.3^2-24:6+(9-7)^3]}:15
=107-{38+[7.9-24:6+23]} :15
=107-{38+[63-4+8]}:15
=107-{38+67}:15
=107-105:15
=107-7=7
Kết quả là 100 Tran Dinh Phuoc Son ơi,
107 -7 mà bằng 7 à ???😶😶😶😶😶
Nhưng cách làm thì đúng rồi đó 😋😋😋😋😋❣❣❣❣❣
![](https://rs.olm.vn/images/avt/0.png?1311)
Vì 24;38 chia cho a dư 3
=> 21;35 chia hết cho a
=> a \(\in\) ƯC(21;35) = {1;7}
Vậy số cần tìm là 7
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107{38 + [7.32 - 24:6 + (9 - 7)3]} : 15
= 107{38 + [7.9 - 24:6 + 23]} : 15
= 107{38 + [63 - 4 + 8]} : 15
= 107{38 + 67} : 15
= 107.105 : 15
= 11235 : 15
= 749
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=107-{38+[7.9-24:6+(9-343]}:15
=107- {38+[7.9-24:6+-334]}:15
=107-{38+-322}:15
=107--284:15
=107--18,93333333
=117,9333333
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107- { 38 + [ 7.32 -24:6 + ( 9-7)3]} :15
= 107- {38+[ 7.9 - 4 + 23]} :15
=107 - {38 + [ 63 - 4 + 8 ]} :15
=107- { 38 + [ 59 +8 ]}:15
=107- {38 + 67} :15
=107 - 105 : 15
=107 - 7
= 100
= -19/36
\(\dfrac{38}{24}:\left(-3\right)=-\dfrac{19}{36}\)