Question

bài 1:

\(a,\frac{3}{8}+\frac{-5}{6}\)

b, \(\frac{15}{12}-\frac{-1}{4}\)

bài 2:

a,\(\frac{-1}{12}-\left(2\frac{5}{8}-\frac{1}{3}\right)\) c, \(-1,75-\left(\frac{-1}{9}-2\frac{1}{18}\right)\)

b, \(\frac{-5}{6}-\left[\frac{-3}{8}+\frac{1}{10}\right]\) d,

Answer 1

Bài 1:

a) Ta có: \(\frac{3}{8}+\frac{-5}{6}\)

\(=\frac{3}{8}-\frac{5}{6}\)

\(=\frac{9}{24}-\frac{20}{24}\)

\(=-\frac{11}{24}\)

b) Ta có: \(\frac{15}{12}-\frac{-1}{4}\)

\(=\frac{15}{12}+\frac{1}{4}\)

\(=\frac{15}{12}+\frac{3}{12}\)

\(=\frac{18}{12}=\frac{3}{2}\)

Bài 2:

a) Ta có: \(-\frac{1}{12}-\left(2\frac{5}{8}-\frac{1}{3}\right)\)

\(=-\frac{1}{12}-\frac{21}{8}+\frac{1}{3}\)

\(=\frac{-2}{24}-\frac{63}{24}+\frac{8}{24}\)

\(=\frac{-57}{24}\)

\(=-\frac{19}{8}\)

b) Ta có: \(\frac{-5}{6}-\left(\frac{-3}{8}+\frac{1}{10}\right)\)

\(=\frac{-5}{6}+\frac{3}{8}-\frac{1}{10}\)

\(=\frac{-100}{120}+\frac{45}{120}-\frac{12}{120}\)

\(=\frac{-67}{120}\)

c) Ta có: \(-1.75-\left(\frac{-1}{9}-2\frac{1}{18}\right)\)

\(=-\frac{7}{4}+\frac{1}{9}+\frac{37}{18}\)

\(=\frac{-63}{36}+\frac{4}{36}+\frac{74}{36}\)

\(=\frac{15}{36}=\frac{5}{12}\)