Bài tập 2 dạng phân số

a) $\frac{3}{4}+\frac{4}{3}-\frac{5}{12}$

= $\frac{9}{12}+\frac{16}{12}-\frac{5}{12}$

= $\frac{9+16-5}{12}$

= $\frac{20}{12}$

= $\frac{5}{3}$

b) $\frac{-5}{-27}-\frac{1}{-18}+\frac{-2}{9}$

= $\frac{10}{51} - \frac{-3}{54} + \frac{-12}{54}$

= $\frac{10 - (-3) + (-12)}{54}$

= $\frac{1}{54}$

c) $\frac{1}{2}-\frac{3}{4}.\frac{-2}{18}+\frac{-3}{7}:\frac{9}{-14}$

= $\frac{1}{2} - \frac{-6}{72} +\frac{-3}{7}.\frac{-14}{9}$

= $\frac{1}{2} - \frac{-1}{12} + \frac{42}{63}$

= $\frac{1}{2} - \frac{-1}{12} + \frac{2}{3}$

= $\frac{6}{12} - \frac{-1}{12} + \frac{8}{12}$

= $\frac{15}{12}$

= $\frac{5}{4}$

d) $\frac{5}{6}:25 -2+\frac{-7}{3}.\frac{2}{7}$

= $\frac{5}{6}.\frac{1}{25} - 2 + \frac{-14}{21}$

= $\frac{5}{150}-2+\frac{-2}{3}$

= $\frac{1}{30} - \frac{60}{30} + \frac{-20}{30}$

= $\frac{-79}{30}$