Question

..Найдите значение выражения:а) (2/7+5/21)*21, б) (7/12-5/9)*12, в) (3/8+5/12)*24, г) (8/11-3/22)*44

Answer 1

Решение:

$[begin{gathered}1)left({frac{2}{7}+frac{5}{{21}}}right)*21=left({frac{6}{{21}}+frac{5}{{21}}}right)*21=left({frac{{6+5}}{{21}}}right)*21=frac{{11}}{{21}}*21=11hfill\2)left({frac{7}{{12}}-frac{5}{9}}right)*12=left({frac{{21}}{{36}}-frac{{20}}{{36}}}right)*12=frac{1}{{36}}*12=frac{1}{3}hfill\3)left({frac{3}{8}+frac{5}{{12}}}right)*24=left({frac{9}{{24}}+frac{{10}}{{24}}}right)*24=frac{{19}}{{24}}*24=19hfill\4)left({frac{8}{{11}}-frac{3}{{22}}}right)*44=left({frac{{16}}{{22}}-frac{3}{{22}}}right)*44=frac{{13}}{{22}}*44=26hfill\end{gathered}]$