x+1/10+x+1/11=x+1/21
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2) => \(-\frac{5}{42}-x=-\frac{18}{28}\) => \(-x=\frac{5}{42}-\frac{18}{28}=\frac{10}{84}-\frac{54}{84}=-\frac{44}{84}\)
=> \(x=\frac{44}{84}=\frac{11}{21}\)
3) => \(x=-\left(\frac{1}{6}+\frac{1}{10}-\frac{1}{15}\right)=-\left(\frac{10}{60}+\frac{6}{60}-\frac{4}{60}\right)=-\frac{12}{60}=-\frac{1}{5}\)
4) => \(\frac{x}{5}=\frac{2}{10}-\frac{1}{5}-\frac{7}{50}=\frac{1}{5}-\frac{1}{5}-\frac{7}{50}=-\frac{7}{50}\)
=> \(x=5.\frac{-7}{50}=-\frac{7}{10}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) Rút gọn P = 3(x – y – 1), thay x = 21, y = -10 tính được P = 90.
b) Rút gọn Q = 64 ( x – 1 ) 3 , thay x = 11 tinh được Q = 64000.
![](https://rs.olm.vn/images/avt/0.png?1311)
(10 - 1 \(\dfrac{1}{6}\) x \(\dfrac{6}{7}\)) : ( 21: \(\dfrac{11}{2}\) + 5\(\dfrac{2}{11}\) )
( 10 \(\dfrac{7}{6}\) x \(\dfrac{6}{7}\) ) : ( 21 : \(\dfrac{11}{2}\) + \(\dfrac{57}{11}\) )
(10 - 1) : ( \(\dfrac{42}{11}\) + \(\dfrac{57}{11}\) )
= 9 : 9
= 1
=> đáp án : 1
=(10 - 1 1/6 x 6/7) : ( 21: 11/2 + 5 2/11)
=( 10 7/6 x 6/7 ) : ( 21 : 11/2 + 57/11)
=(10 - 1) : ( 42/11 + 57/11 )
= 9 : 9
=1
![](https://rs.olm.vn/images/avt/0.png?1311)
=(10 - 1 1/6 x 6/7) : ( 21: 11/2 + 5 2/11)
=( 10 7/6 x 6/7 ) : ( 21 : 11/2 + 57/11)
=(10 - 1) : ( 42/11 + 57/11 )
= 9 : 9
=1
![](https://rs.olm.vn/images/avt/0.png?1311)
=(10 - 1 1/6 x 6/7) : ( 21: 11/2 + 5 2/11)
=( 10 7/6 x 6/7 ) : ( 21 : 11/2 + 57/11)
=(10 - 1) : ( 42/11 + 57/11 )
= 9 : 9
=1
![](https://rs.olm.vn/images/avt/0.png?1311)
Câu 1:
\(=\dfrac{21}{31}+\dfrac{1}{3}-\dfrac{44}{53}+\dfrac{10}{31}-\dfrac{9}{53}=\dfrac{1}{3}\)
Câu 2:
1: =>1,3x=-1,31
=>130x=-131
=>x=-131/130
2: =>(4,5-2x)=11/14:(-11/7)=-7/14=-1/2=-0,5
=>2x=5
=>x=5/2
![](https://rs.olm.vn/images/avt/0.png?1311)
1> a) \(\frac{5}{7}x4:\frac{5}{9}=\frac{5}{7}:\frac{5}{9}x4=\frac{5}{7}x\frac{9}{5}x4=\frac{9}{7}x4=\frac{9x4}{7}=\frac{36}{7}\)
\(b,8x\frac{2}{3}:\frac{1}{2}=8x\frac{2}{3}x\frac{2}{1}=8x2x\frac{2}{3}=16x\frac{2}{3}=\frac{32}{3}\)
\(c,6:\frac{3}{5}-\frac{7}{6}x\frac{6}{7}=6x\frac{5}{3}-1=10-1=9\)
\(\frac{21}{5}x\frac{10}{11}+\frac{57}{11}=\frac{42}{11}+\frac{57}{11}=\frac{99}{11}=9\)
2) a) \(\frac{35}{9}:x=\frac{35}{6}\)
\(x=\frac{35}{9}:\frac{35}{6}\)
\(x=\frac{35}{9}x\frac{6}{35}\)
\(x=\frac{2}{3}\)
b) \(\left(\frac{1}{1x2}+\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+\frac{1}{5x6}\right)x10-X=0\)
\(\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+.....+\frac{1}{5}-\frac{1}{6}\right)x10-X=0\)
\(\left(\frac{1}{1}-\frac{1}{6}\right)x10-X=10\)
\(\frac{5}{6}x10-X=0\)
\(X=\frac{5}{6}x10=\frac{25}{3}\)
Đúng nha !!!!
1/a/\(\frac{5}{7}\cdot4:\frac{5}{9}=\frac{20}{7}:\frac{5}{9}=\frac{20}{7}\cdot\frac{9}{5}=\frac{36}{7}\)
b/\(8\cdot\frac{2}{3}:\frac{1}{2}=\frac{16}{3}:\frac{1}{2}=\frac{16}{3}\cdot\frac{2}{1}=\frac{32}{3}\)
c/\(6:\frac{3}{5}-\frac{7}{6}\cdot\frac{6}{7}=6\cdot\frac{5}{3}-1=10-1=9\)
2/a/\(\frac{35}{9}:x=\frac{35}{6}\)
\(x=\frac{35}{9}:\frac{35}{6}=\frac{35}{9}\cdot\frac{6}{35}\)
\(x=\frac{2}{3}\)
b/\(\left(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}\right)\cdot10-x=0\)
\(\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}\right)\cdot10-x=0\)
\(\left(\frac{30}{60}+\frac{10}{60}+\frac{5}{60}+\frac{2}{30}\right)\cdot10-x=0\)
\(\frac{47}{60}\cdot10-x=0\)
\(\frac{47}{6}-x=0\)
\(x=\frac{47}{6}-0\)
\(x=\frac{47}{6}\)
\(x\) + \(\dfrac{1}{10}\) + \(x\) + \(\dfrac{1}{11}\) = \(x\) + \(\dfrac{1}{21}\)
\(x+x-x\) = \(\dfrac{1}{21}\) - \(\dfrac{1}{10}\) - \(\dfrac{1}{11}\)
\(x\) = - \(\dfrac{331}{2310}\)
\(x+\dfrac{1}{10}+x+\dfrac{1}{11}=x+\dfrac{1}{21}\)
\(x+x-x=\dfrac{1}{21}-\dfrac{1}{10}-\dfrac{1}{11}\)
\(x=\dfrac{-11}{210}-\dfrac{1}{11}\)
\(x=\dfrac{-331}{2310}\)