-3/5 . 2/7 + -3/5 . 5/7 + 2 3/5 ( 2 3/5 là hỗ số ) -3/4.4/7+-3/5.3/7+2/-5 1,4. 15/49 – (4/5+2/3):2 1/5 07/11/2021 Bởi Charlie -3/5 . 2/7 + -3/5 . 5/7 + 2 3/5 ( 2 3/5 là hỗ số ) -3/4.4/7+-3/5.3/7+2/-5 1,4. 15/49 – (4/5+2/3):2 1/5
a, $\frac{-3}{5}.\frac{2}{7}+\frac{-3}{5}.\frac{5}{7}+\frac{13}{5}$ $= \frac{-3}{5}(\frac{2}{7}+\frac{5}{7})+\frac{13}{5}$ $=\frac{-3}{5}+\frac{13}{5}=2$ b, $\frac{-3}{4}\frac{4}{7}+\frac{-3}{5}.\frac{3}{7}+\frac{2}{-5}$ $= \frac{-3}{7}+\frac{-9}{35}+ \frac{-2}{5}$ $= \frac{-24}{35}+\frac{-2}{5}$ $= \frac{-38}{35}$ c, $1,4.\frac{15}{49}-(\frac{4}{5}+\frac{2}{3}): \frac{11}{5}$ $= \frac{3}{7}-\frac{22}{15}.\frac{5}{11}$ $=\frac{3}{7}-\frac{2}{3}$ $= -\frac{5}{21}$ Bình luận
a,
$\frac{-3}{5}.\frac{2}{7}+\frac{-3}{5}.\frac{5}{7}+\frac{13}{5}$
$= \frac{-3}{5}(\frac{2}{7}+\frac{5}{7})+\frac{13}{5}$
$=\frac{-3}{5}+\frac{13}{5}=2$
b,
$\frac{-3}{4}\frac{4}{7}+\frac{-3}{5}.\frac{3}{7}+\frac{2}{-5}$
$= \frac{-3}{7}+\frac{-9}{35}+ \frac{-2}{5}$
$= \frac{-24}{35}+\frac{-2}{5}$
$= \frac{-38}{35}$
c,
$1,4.\frac{15}{49}-(\frac{4}{5}+\frac{2}{3}): \frac{11}{5}$
$= \frac{3}{7}-\frac{22}{15}.\frac{5}{11}$
$=\frac{3}{7}-\frac{2}{3}$
$= -\frac{5}{21}$