Bài 4:
a) $\frac{21}{25}$ . $\frac{11}{9}$ . $\frac{5}{7}$
= $\frac{21}{25}$ . $\frac{5}{7}$ . $\frac{11}{9}$
= $\frac{3}{5}$ . $\frac{11}{9}$
= $\frac{11}{15}$
b) $\frac{5}{23}$ . $\frac{17}{26}$ + $\frac{5}{23}$ . $\frac{9}{26}$
= $\frac{5}{23}$ . ( $\frac{17}{26}$ + $\frac{9}{26}$ )
= $\frac{5}{23}$ . 1
= $\frac{5}{23}$
c) ( $\frac{3}{29}$ - $\frac{1}{5}$ ) . $\frac{29}{3}$
= $\frac{3}{29}$ . $\frac{29}{3}$ - $\frac{1}{5}$ . $\frac{29}{3}$
= 1 - $\frac{29}{15}$
= $\frac{-14}{15}$
Xin hay nhất
