Bài 1. Tính:
a) \( \frac{3}{10}\) x \( \frac{4}{9}\) ; b) \( \frac{6}{5}:\frac{3}{7}\) ; c) \( \frac{3}{4}\) x \( \frac{2}{5}\) ; d) \( \frac{5}{8}:\frac{1}{2}\) .
e) 4 x \( \frac{3}{8}\) ; f) 3 : \( \frac{1}{2}\) ; g) \( \frac{1}{2}\) : 3 .
a) \( \frac{3}{10}\) x \( \frac{4}{9}\) \( =\frac{3.4}{10.9}=\frac{2}{5.3}=\frac{2}{15}\) ;
b) \( \frac{6}{5}:\frac{3}{7}\) \( =\frac{6}{5}.\frac{7}{3}=\frac{2.7}{5}=\frac{14}{5}\) ;
Advertisements (Quảng cáo)
c) \( \frac{3}{4}.\frac{2}{5}=\frac{3.2}{4.5}=\frac{3}{2.5}=\frac{3}{10}\) ;
d) \( \frac{5}{8}:\frac{1}{2}\) \( =\frac{5}{8}.\frac{2}{1}=\frac{5.2}{8.1}=\frac{5}{4}\) ;
e) 4 x \( \frac{3}{8}\) \( =\frac{4}{1}.\frac{3}{8}=\frac{4.3}{1.8}=\frac{3}{2}\) ;
f) 3 : \( \frac{1}{2}\) \( =\frac{3}{1}:\frac{1}{2}=\frac{3}{1}.\frac{2}{1}=6\) ;
g) \( \frac{1}{2}\) : 3 = \( \frac{1}{2}:\frac{3}{1}=\frac{1}{2}.\frac{1}{3}=\frac{1}{6}\) .