Nội dung bài giảng
Bài 1. Tính:
a) \( \frac{7}{9}×\frac{4}{5}\) ; b) \( 2\frac{1}{4}×3\frac{2}{5}\) ; c) \( \frac{1}{5}:\frac{7}{8}\) ; d) \( 1\frac{1}{5}:1\frac{1}{3}\) .
Bài làm:
a) \( \frac{7}{9}×\frac{4}{5}\) \( =\frac{7×4}{9×5}=\frac{28}{45}\) ;
b) \( 2\frac{1}{4}×3\frac{2}{5}\) \( =\frac{9}{4}×\frac{17}{5}=\frac{153}{20}\) ;
c) \( \frac{1}{5}:\frac{7}{8}\) \( =\frac{1}{5}×\frac{8}{7}=\frac{8}{35}\) ;
d) \( 1\frac{1}{5}:1\frac{1}{3}\) \( =\frac{6}{5}:\frac{4}{3}=\frac{6}{5}×\frac{3}{4}=\frac{9}{10}\) ;