Bài tập về thực hiện phép tính cộng, trừ

Bài tập về thực hiện phép tính cộng, trừ.

a) $\frac{5}{11} + \frac{23}{29} - \frac{16}{11}$

= $(\frac{5}{11} - \frac{16}{11}) + \frac{23}{29}$

= $- 1 + \frac{23}{29}$

= $\frac{- 29}{29} + \frac{23}{29}$

= $\frac{- 6}{29}$

b) $13 \frac{2}{5} + \frac{15}{23} + 1 \frac{6}{10}$

= $(13 + 1) + (\frac{2}{5} + \frac{15}{23} + \frac{6}{10})$

= $14 + (\frac{92}{230} + \frac{150}{230} + \frac{138}{230})$

= $14 + \frac{38}{23}$

= $15 \frac{15}{23}$

c) $\frac{2}{5} - (\frac{- 2}{7}) - \frac{14}{10}$

= $(\frac{2}{5} - \frac{14}{10}) + \frac{2}{7}$

= $(\frac{4}{10} - \frac{14}{10}) + \frac{2}{7}$

= $- 1 + \frac{2}{7}$

= $\frac{- 5}{7}$

a) P = $\frac{2}{3} - (- \frac{1}{4}) + \frac{3}{5} - \frac{7}{45} - (- \frac{5}{9}) + \frac{1}{12} + \frac{1}{35}$

= $(\frac{2}{3} + \frac{1}{4} + \frac{1}{12}) + (\frac{3}{5} + \frac{5}{9} - \frac{7}{45}) + \frac{1}{35}$

= $1 + 1 + \frac{1}{35}$

= $2 \frac{1}{35}$

b) Q = $(5 - \frac{3}{4} + \frac{1}{5}) - (6 + \frac{7}{4} - \frac{8}{5}) - (2 - \frac{5}{4} + \frac{16}{5})$

= $(5 - 6 - 2) + (\frac{- 3}{4} - \frac{7}{4} + \frac{5}{4}) + (\frac{1}{5} + \frac{8}{5} - \frac{16}{5})$

= $- 3 - \frac{5}{4} - \frac{7}{5}$

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

= $- 5 \frac{13}{20}$

3. Ví dụ:

a) $\frac{- 99}{100} = - 1 - \frac{- 1}{100} = \frac{- 101}{100} - \frac{- 2}{100}$

b) $5 \frac{3}{4} = 5 - \frac{- 3}{4}$