Question

Найдите значение выражения:
а)25*(7/10+3/5+1/2)
б)30:(5/7+1/28+3/4)
в)(5/12+1/6+3/8):15/16
г)(3/5-4/15)*(1/2-1/3)
д)(2/3+5/9):(1/9+1/3)
е)(7/8+6/7)*(7/8-6/7)

Answer 1

а) 
$25(frac{7}{10}+frac{3}{5}+н)=25(0,7+0,6+0,5)=25*1,8=45;$
б) 
$frac{30}{frac{5}{7}+frac{1}{28}+frac{3}{4}}=frac{30}{frac{20}{28}+frac{1}{28}+frac{21}{28}}=frac{30}{frac{42}{28}}=30*frac{28}{42}=5*frac{28}{7}=20;$
в) 
$frac{frac{5}{12}+frac{1}{6}+frac{3}{8}}{frac{15}{16}}=frac{frac{10}{24}+frac{4}{24}+frac{9}{24}}{frac{15}{16}}=frac{23}{24}:frac{15}{16}=frac{23}{24}*frac{16}{15}=frac{23}{3}*frac{2}{15}=frac{46}{45}=1frac{1}{45};$
г) 
$(frac{3}{5}-frac{4}{15})(frac{1}{2}-frac{1}{3})=(frac{9}{15}-frac{4}{15})(frac{3}{6}-frac{2}{6})=frac{5}{15}*frac{1}{6}=frac{5}{90}=frac{1}{18};$
д) 
$frac{frac{2}{3}+frac{5}{9}}{frac{1}{9}+frac{1}{3}}=frac{frac{6}{9}+frac{5}{9}}{frac{1}{9}+frac{3}{9}}=frac{11}{9}:frac{4}{9}=frac{11}{9}*frac{9}{4}=frac{11}{4}=2,75;$
е) 
$(frac{7}{8}+frac{6}{7})(frac{7}{8}-frac{6}{7})=(frac{49}{56}+frac{48}{56})(frac{49}{56}-frac{48}{56})=frac{97}{56}*frac{1}{56}=frac{97}{3136}.$