85 : (x-7) =17
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Ko còn bài nào giải làm tạm bài này chứ mk cũng ko muốn làm n bài dễ
a)\(45-\frac{x}{3}=\frac{56}{7}\)
\(\Leftrightarrow\frac{x}{3}=45-\frac{56}{7}\)
\(\Leftrightarrow\frac{x}{3}=37\)
\(\Rightarrow x=171\)
b)\(x-\frac{7}{85}=\frac{4}{17}\)
\(\Leftrightarrow x=\frac{4}{17}+\frac{7}{85}\)
\(\Rightarrow x=\frac{27}{85}\)
a)45—x/3=56/7
45—x/3=8
x/3=45—8
x/3=37
x=37x3
x=111
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\(A=\frac{34}{7.13}+\frac{51}{13.22}+\frac{85}{22.37}+\frac{68}{37.49}\)
\(=\frac{17.2}{7.13}+\frac{17.3}{13.22}+\frac{17.5}{22.37}+\frac{17.4}{37.49}\)
\(=17\left(\frac{2}{7.13}+\frac{3}{13.22}+\frac{5}{22.37}+\frac{4}{37.49}\right)\)
\(=\frac{17}{3}\left(\frac{6}{7.13}+\frac{9}{13.22}+\frac{15}{22.37}+\frac{12}{37.49}\right)\)
\(=\frac{17}{3}\left(\frac{1}{7}-\frac{1}{13}+\frac{1}{13}-\frac{1}{22}+...+\frac{1}{37}-\frac{1}{49}\right)\)
\(=\frac{17}{3}\left(\frac{1}{7}-\frac{1}{49}\right)\)\(=\frac{17}{3}.\frac{6}{49}=\frac{17.2}{49}=\frac{34}{49}\)
Có : \(\frac{17}{24}=\frac{34}{48}\)
Vì 48 < 49 => \(\frac{34}{48}>\frac{34}{49}\). Hay \(\frac{17}{24}>A\)
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a,x/9=5/3 = x=15
b,17/x=85/105 = x = 21
c,6/8=15/x = x = 20
d,x/8=2/3 = x = 6
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Bài 6:
a)\(\left(-18\right)-\left(-3\right)-12\)
\(=\left(-18\right)+3-12\)
\(=-15-12\)
\(=-27\)
b)\(85.\left(35-27\right)-35.\left(85-27\right)\)
\(=85.35-85.27-35.85+35.27\)
\(=85.\left(35-27-35\right)+35.27\)
\(=85.\left(-27\right)+35.27\)
\(=27.\left(-85+35\right)\)
\(=27.\left(-50\right)\)
\(=-1350\)
c)\(\left(-45\right).69+31.\left(-45\right)\)
\(=\left(-45\right).\left(69+31\right)\)
\(=\left(-45\right).100\)
\(=-4500\)
Bài 7:
a)\(\left(2-x\right)+10=-14\)
\(\Rightarrow2-x=-24\)
\(\Rightarrow x=26\)
b)\(14.\left|x\right|=28\)
\(\Rightarrow\left|x\right|=2\)
\(\Rightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)
c)\(31-\left(17+x\right)=55\)
\(\Rightarrow17+x=-24\)
\(\Rightarrow x=-41\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(-2,4\cdot\dfrac{17}{4}+\dfrac{12}{7}\cdot\left(-\dfrac{85}{6}\right)-2,4\cdot\left(-5\dfrac{5}{4}\right)-\dfrac{12}{7}\cdot\left(-\dfrac{71}{6}\right)\)
\(=-2,4\cdot\dfrac{17}{4}-2,4\cdot\left(-\dfrac{25}{4}\right)+\dfrac{12}{7}\cdot\left(-\dfrac{85}{6}\right)+\dfrac{12}{7}\cdot\dfrac{71}{6}\)
\(=-2,4\cdot\left(\dfrac{17}{4}-\dfrac{25}{4}\right)+\dfrac{12}{7}\cdot\left(-\dfrac{85}{6}+\dfrac{71}{6}\right)\)
\(=-2,4\cdot\left(-2\right)+\dfrac{12}{7}\cdot\left(-\dfrac{7}{3}\right)\)
\(=4,8-4\)
\(=0,8\)
#\(Toru\)
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a) \(\dfrac{25}{37}\times\dfrac{18}{29}+\dfrac{18}{29}\times\dfrac{12}{37}\)
\(=\dfrac{18}{29}\times\left(\dfrac{25}{37}+\dfrac{12}{37}\right)\)
\(=\dfrac{18}{29}\times\dfrac{37}{37}\)
\(=\dfrac{18}{29}\times1\)
\(=\dfrac{18}{29}\)
b) \(\dfrac{31}{85}\times\dfrac{11}{19}+\dfrac{31}{85}\times\dfrac{12}{19}-\dfrac{42}{19}\times\dfrac{31}{85}\)
\(=\dfrac{31}{85}\times\left(\dfrac{11}{19}+\dfrac{12}{19}-\dfrac{42}{19}\right)\)
\(=\dfrac{31}{85}\times\dfrac{-19}{19}\)
\(=\dfrac{31}{85}\times-1\)
\(=-\dfrac{31}{85}\)
c) \(\dfrac{16}{53}:\dfrac{17}{9}-\dfrac{16}{53}:\dfrac{17}{8}\)
\(=\dfrac{16}{53}:\left(\dfrac{9}{17}-\dfrac{8}{17}\right)\)
\(=\dfrac{16}{53}:\dfrac{1}{17}\)
\(=\dfrac{16}{901}\)
c) \(\dfrac{1}{5}\times\dfrac{12}{31}\times\dfrac{4}{3}+\dfrac{19}{31}\times\dfrac{4}{15}\)
\(=\dfrac{4}{15}\times\dfrac{12}{31}+\dfrac{19}{31}\times\dfrac{4}{15}\)
\(=\dfrac{4}{15}\times\left(\dfrac{12}{31}+\dfrac{19}{31}\right)\)
\(=\dfrac{4}{15}\times\dfrac{31}{31}\)
\(=\dfrac{4}{15}\times1\)
\(=\dfrac{4}{15}\)
a: =18/29*(25/37+12/37)
=18/29
b: =31/85(11/19+12/19-42/19)
=-31/85
c; =16/53(9/17+8/17)=16/53
d: =4/15(12/31+19/31)=4/15
ta có: (x-7)=85/17
x-7=5
=>x=7+5=12
85 : (x-7) =17
=>x-7 =5
=>x=12