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a. \(\dfrac{-3}{5}\)
b. \(\dfrac{-2}{3}\) c. \(\dfrac{4}{39}\) d. \(\dfrac{26}{45}\)
\(\frac{-5}{12}+\frac{-1}{4}=\frac{-5}{12}+\frac{-3}{12}=\frac{-5+-3}{12}=\frac{-8}{12}=\frac{-2}{3}\)
\(\frac{5}{12}+\frac{-3}{28}=\frac{35}{84}+\frac{-9}{84}=\frac{35+\left(-9\right)}{84}=\frac{26}{84}=\frac{13}{42}\)
\(\frac{-7}{15}+\frac{3}{35}=\frac{-49}{105}+\frac{9}{105}=\frac{-49+9}{105}=\frac{-40}{105}=\frac{-8}{21}\)
\(\frac{-5}{7}+\frac{-3}{4}=\frac{-20}{28}+\frac{-21}{28}=\frac{-20+\left(-21\right)}{28}=\frac{-41}{28}\)
a) \(\frac{1}{6}+\frac{-5}{6}\)
\(=\frac{1+\left(-5\right)}{6}\)
\(=\frac{-4}{6}=\frac{-2}{3}\)
b) \(\frac{6}{13}+\frac{-14}{39}\)
\(=\frac{18}{39}+\frac{-14}{39}\)
\(=\frac{4}{39}\)
c) \(\frac{4}{5}+\frac{4}{-18}\)
\(=\frac{4}{5}+\frac{-4}{18}\)
\(=\frac{72}{90}+\frac{-20}{90}\)
\(=\frac{52}{90}=\frac{26}{45}\)
\(\frac{7}{14}+\frac{9}{-36}=\frac{7}{14}+\frac{-9}{36}=\frac{126}{252}+\frac{-63}{252}=\frac{126+\left(-63\right)}{252}=\frac{63}{252}=\frac{1}{4}\)
- (1/2-1/3-1/6).(3/8+34/88-345/888)
= (3/6-2/6-1/6).(3/8+34/88-345/888)
= 0.(3/8+434/88-345/888)=0
2. 8/3.2/5.3/8.10.19/92
= (8/3.3/8).(2/5.10).19/92
= 1.4.19/92
= 76/92
1) \(\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\left(\frac{3}{8}+\frac{34}{88}+\frac{345}{888}\right)=\left(\frac{3}{6}-\frac{2}{6}-\frac{1}{6}\right)\left(\frac{3}{8}+\frac{34}{88}+\frac{345}{888}\right)\)
\(=\left(\frac{1}{6}-\frac{1}{6}\right)\left(\frac{3}{8}+\frac{34}{88}+\frac{345}{888}\right)\)
\(=0\cdot\left(\frac{3}{8}+\frac{34}{88}+\frac{345}{888}\right)=0\)(số nào nhân với 0 cũng bằng 0)
2) \(\frac{8}{3}\cdot\frac{2}{5}\cdot\frac{3}{8}\cdot10\cdot\frac{19}{92}=\frac{8\cdot2\cdot3\cdot10\cdot19}{3\cdot5\cdot8\cdot92}\)
\(=\frac{2\cdot10\cdot19}{5\cdot92}=\frac{2\cdot2\cdot5\cdot19}{5\cdot2\cdot2\cdot23}=\frac{19}{23}\)
7/-25+-8/25=-7/25+-8/25=-15/25=-3/5
=-7/25+-8/25
=-15/25
=-3/5
k nha