a)\(=\frac{-3}{7}+\frac{15}{26}-\frac{2}{13}+\frac{3}{7}\)

\(=\left(\frac{-3}{7}+\frac{3}{7}\right)-\left(\frac{15}{26}+\frac{2}{13}\right)\)

\(=0-\frac{19}{26}\)

\(=-\frac{19}{26}\)

c)\(=\frac{-11}{23}.\left(\frac{6}{7}+\frac{8}{7}\right)-\frac{1}{23}\)

\(=\frac{-11}{23}.2-\frac{1}{23}\)

\(=\frac{-22}{23}-\frac{1}{23}\)

\(=-1\)

sao bn phũ với mk thế:(( đx ko giải lại còn nói thế

Nó dễ mà :(

Bài 1:

a) Ta có: \(\frac{-5}{7}+\frac{2}{7}+\frac{4}{-9}+\frac{4}{9}\)

\(=-\frac{3}{7}+\frac{-4}{9}+\frac{4}{9}\)

\(=-\frac{3}{7}\)

b) Ta có: \(\left(\frac{1}{2}:\frac{3}{4}\right)^2\)

\(=\left(\frac{1}{2}\cdot\frac{4}{3}\right)^2\)

\(=\left(\frac{2}{3}\right)^2=\frac{4}{9}\)

c) Ta có: \(\frac{1}{2}+\frac{3}{4}-\left(\frac{4}{5}+\frac{3}{4}\right)\)

\(=\frac{1}{2}+\frac{3}{4}-\frac{4}{5}-\frac{3}{4}\)

\(=\frac{1}{2}-\frac{4}{5}\)

\(=\frac{5}{10}-\frac{8}{10}=\frac{-3}{10}\)

d) Ta có: \(5^6:5^4+2^3\cdot2^2-225:15^2\)

\(=5^2+2^5-\frac{15^2}{15^2}\)

\(=25+32-1\)

\(=56\)

e) Ta có: \(\frac{7}{23}+\frac{4}{17}-\frac{7}{23}+\frac{13}{17}\)

\(=\frac{4}{17}+\frac{13}{17}\)

\(=\frac{17}{17}=1\)

g) Ta có: \(19\frac{1}{4}\cdot\frac{7}{12}-15\frac{1}{4}\cdot\frac{7}{12}\)

\(=\frac{7}{12}\left(19+\frac{1}{4}-15-\frac{1}{4}\right)\)

\(=\frac{7}{12}\cdot4=\frac{7}{3}\)

a) \(\frac{-3}{7}+\frac{15}{26}-\left(\frac{2}{13}-\frac{3}{7}\right)=\frac{-3}{7}+\frac{15}{26}-\frac{2}{13}+\frac{3}{7}=\left(\frac{-3}{7}+\frac{3}{7}\right)+\left(\frac{15}{26}-\frac{2}{13}\right)\)

\(=\frac{15-4}{26}=\frac{11}{26}\)

c) \(\frac{-11}{23}.\frac{6}{7}+\frac{8}{7}.\frac{-11}{23}-\frac{1}{23}=\frac{-11}{23}.\left(\frac{6}{7}+\frac{8}{7}\right)-\frac{1}{23}\)

\(=\frac{-11}{23}.2-\frac{1}{23}=\frac{-22-1}{23}=\frac{-23}{23}=-1\)

a: x/5=32/80

nên x/5=2/5

hay x=2

13/x=26/30

nên 13/x=13/15

hay x=15

-x/7=22/-77

=>x/7=2/7

hay x=2

b: x/9=28/36

=>x/9=7/9

hay x=7

-10/x=50/55

=>-10/x=10/11

hay x=-11

a)

1) x/5 = 32/80

\(x : 5 = 32 : 80\) \(x = 5 \cdot \frac{32}{80}\) \(x = 5 \cdot \frac{2}{5}\) \(x = 2\)

2) 13/x = 26/30

\(13 : x = 26 : 30\) \(13 \cdot 30 = x \cdot 26\) \(390 = 26 x\) \(x = 390 : 26\) \(x = 15\)

3) -x/7 = 22/(-77)

\(- x : 7 = 22 : \left(\right. - 77 \left.\right)\) \(- x = 7 \cdot \frac{22}{- 77}\) \(- x = 7 \cdot \left(\right. - \frac{2}{7} \left.\right)\) \(- x = - 2\) \(x = 2\)

b)

1) x/9 = 28/36

\(x : 9 = 28 : 36\) \(x = 9 \cdot \frac{28}{36}\) \(x = 9 \cdot \frac{7}{9}\) \(x = 7\)

2) -10/x = 50/55

\(- 10 : x = 50 : 55\) \(- 10 \cdot 55 = 50 x\) \(- 550 = 50 x\) \(x = - 550 : 50\) \(x = - 11\)

3) 23/(-x) = 46/50

\(23 : \left(\right. - x \left.\right) = 46 : 50\) \(23 \cdot 50 = 46 \left(\right. - x \left.\right)\) \(1150 = - 46 x\) \(x = 1150 : \left(\right. - 46 \left.\right)\) \(x = - 25\)

✅ Kết quả cuối cùng

a)

1. x = 2
2. x = 15
3. x = 2

b)

1. x = 7
2. x = -11
3. x = -25

a) \(x.\left(\frac{2}{3}-\frac{3}{2}\right)=\frac{5}{12}\)

\(\Leftrightarrow x.\left(-\frac{5}{6}\right)=\frac{5}{12}\)

\(\Leftrightarrow x=-\frac{1}{2}\)

b) \(\frac{7}{9}:\left(2+\frac{3}{4}x\right)=\frac{8}{27}\)

\(\Leftrightarrow2+\frac{3}{4}x=\frac{21}{8}\)

\(\Leftrightarrow\frac{3}{4}x=\frac{5}{8}\)

\(\Leftrightarrow x=\frac{5}{6}\)

c) \(\frac{3}{5}.\left(3x-3,7\right)=-\frac{57}{10}\)

\(\Leftrightarrow3x-3,7=-\frac{19}{2}\)

\(\Leftrightarrow3x=-\frac{29}{5}\)

\(\Leftrightarrow x=-\frac{29}{15}\)

Bài 1:

a) \(\frac{25}{4}+\frac{-5}{4}=\frac{25-5}{4}=\frac{20}{4}=5\)

b)\(\frac{-5}{9}+\left(\frac{-2}{7}\right)=\frac{-35}{63}+\left(\frac{-18}{63}\right)=\frac{-53}{63}\)

c) \(\frac{1}{4}+\frac{9}{11}+\frac{7}{4}+\left(\frac{-2}{11}\right)=\left(\frac{1}{4}+\frac{7}{4}\right)+\left(\frac{-2}{11}+\frac{9}{11}\right)=2+\frac{7}{11}=\frac{22+7}{11}=\frac{29}{11}\)

d) \(\frac{-5}{19}.\frac{8}{19}+\left(\frac{-14}{19}\right).\frac{11}{19}=\frac{-40}{361}-\frac{151}{361}=-\frac{191}{361}\)

Bài 2: 

a) \(x+\frac{5}{9}=\frac{-8}{9}\)  \(\Leftrightarrow x=\frac{-8}{9}-\frac{5}{9}\)  \(\Leftrightarrow x=-\frac{13}{9}\)

b) \(\frac{-1}{8}-x=\frac{9}{20}\)  \(\Leftrightarrow x=\frac{-1}{8}-\frac{9}{20}\)  \(\Leftrightarrow x=\frac{-5}{40}-\frac{18}{40}\)  \(\Leftrightarrow x=-\frac{23}{40}\)

c) (x + 5)³ - 12 = 15

\(\Leftrightarrow\)(x + 5)³ = 27

\(\Leftrightarrow\)x + 5 = 3

\(\Leftrightarrow\)x = -2

d) \(\left|x-3\right|-\frac{4}{15}=\frac{26}{15}\)  \(\Leftrightarrow\left|x-3\right|=2\)  \(\Leftrightarrow\orbr{\begin{cases}x-3=2\\x-3=-2\end{cases}}\)  \(\Leftrightarrow\orbr{\begin{cases}x=5\\x=1\end{cases}}\)

a. \(\frac{-3}{7}+\frac{15}{26}-\left(\frac{2}{13}-\frac{3}{7}\right)=\frac{-3}{7}+\frac{15}{26}-\frac{2}{13}+\frac{3}{7}=\frac{15}{13.2}-\frac{2}{13}=\frac{15}{13.2}-\frac{2.2}{13.2}=\frac{15-4}{26}=\frac{11}{26}\)

C. \(\frac{-11}{23}.\frac{6}{7}+\frac{8}{7}.\frac{-11}{23}-\frac{1}{23}=\frac{1}{23}.\left(-11.\frac{6}{7}-11.\frac{8}{7}-1\right)=\frac{1}{23}.\left(-22-1\right)=\frac{1}{23}.\left(-23\right)=-1\)