2) 5/6 . |3/8-x|-(-7/8+11/12-5/6)=1
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Bài 1:
a: \(x=\dfrac{2}{3}:\dfrac{3}{5}=\dfrac{2}{3}\cdot\dfrac{5}{3}=\dfrac{10}{9}\)
b: \(x=\dfrac{17}{8}:\dfrac{7}{17}=\dfrac{17}{8}\cdot\dfrac{17}{7}=\dfrac{289}{56}\)
c: \(x=-\dfrac{3}{4}:\dfrac{7}{12}=\dfrac{-3}{4}\cdot\dfrac{12}{7}=\dfrac{-63}{28}=-\dfrac{9}{4}\)
d: \(\Leftrightarrow x\cdot\dfrac{1}{6}=\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{1}{4}\)
hay \(x=\dfrac{1}{4}:\dfrac{1}{6}=\dfrac{3}{2}\)
e: \(\Leftrightarrow\dfrac{1}{2}:x=-4-\dfrac{1}{3}=-\dfrac{17}{3}\)
hay \(x=-\dfrac{1}{2}:\dfrac{17}{3}=\dfrac{-3}{34}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có: \(\dfrac{5}{6}\left|\dfrac{3}{8}-x\right|-\left(-\dfrac{7}{8}+\dfrac{11}{12}-\dfrac{5}{6}\right)=1\)
\(\Leftrightarrow\dfrac{5}{6}\cdot\left|x-\dfrac{3}{8}\right|=\dfrac{5}{24}\)
\(\Leftrightarrow\left|x-\dfrac{3}{8}\right|=\dfrac{1}{4}\)
\(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{3}{8}=\dfrac{1}{4}\\x-\dfrac{3}{8}=-\dfrac{1}{4}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{8}\\x=\dfrac{1}{8}\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1: =72/90+65/90=137/90
2: =24/56-77/56=-53/56
3: =-7/10+4/5=1/10
4: =15/100-4/100=11/100
5: =4/6-5/6=-1/6
6: =10/40-15/40-76/40=-81/40
7: =-9/10+7/18
=-81/90+35/90=-46/90=-23/45
8: =27/90-55/90=-28/90=-14/45
9: =36/60-50/60-35/60=-49/60
10: =-4/9+5/6-3/8
=-32/72+60/72-27/72
=1/72
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{5}{6}\) + \(\dfrac{7}{8}\)
= \(\dfrac{5\times4}{6\times4}\) + \(\dfrac{7\times3}{8\times3}\)
= \(\dfrac{20}{24}\) + \(\dfrac{21}{24}\)
= \(\dfrac{41}{24}\)
5/6 + 7/8 = 41/24
2 + 2/3 = 8/3
7/9 - 1/7 = 40/63
1-1/11 =10/11
2x17/81 = 34/81
9/11 : 5/6 = 54/55
3: 12/25 = 25/4
Tick cho mik nhé.
Chúc bạn học tốt nha !
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1+2+3+4+5+6+7+8+9+10+11+12+13-1-2-3-4-5-6-7-8-9-10-11-12
=(1-1)+(2-2)+(3-3)+(4-4)+(5-5)+(6-6)+(7-7)+(8-8)+(9-9)+(10-10)+(11-11)+(12-12)+13
= 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 13
= 13
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 - 1 - 2 - 3 - 4 - 5 - 6 - 7- 8 - 9 - 10
= (1+12) + (2+11) + (3+10) + ( 4+9) + (5+8) + (6+7) + 13 - (1+11) - ( 2+10) - ( 3+9) - (4+8) - (5+7) + 6 + 12
= 13 * 7 - 12 * 6 + 6
= 13
Ai k mk mk k lại
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
5/-6+-5/12 +7/18 = -31/36
2/9+-3/10+-7/10 = 2/9+(-3/10+-7/10)=2/9+(-1)=7/9
-11/6 +2/5 +-1/6 =2/5 +(-11/6+-1/6)=2/5 + -2 =-8/5
-5/8+12/7+13/8+2/7 =(-5/8+13/8)+(12/7+2/7)=1+2=3