Question

8) Вычислите: а); б); г); д); ж); Заранее спасибо.

Answer 1

А) вынесем 12 за скобку: 12(5+9) 14
---------- = ---
12•21 21

Б) 14(5-2) 3
--------- = --
14•2 2

Г) 81(17-15) 2
------------- = --
81(17+4) 21

Д) 2,4•6,3•2•3,5 1
--------------------- = --
6,3•2,4•2•3,5•9 9

Answer 2

А) 
$\frac{12*5+12*9}{12*21}=\frac{12(5+9)}{12*21}=\frac{14}{21}=\frac{2}{3}$

б) 
$\frac{14*5-14*2}{28}=\frac{14(5-2)}{28}=\frac{3}{2}=1,5$

в) 
$\frac{15*17-15*6}{15*17+15*6}=\frac{15(17-6)}{15(17+6)}=\frac{17-6}{17+6}=\frac{11}{23}$

г) 
$\frac{81*17-15*81}{81*17+81*4}=\frac{81(17-15)}{81(17+4)}=\frac{17-15}{17+4}=\frac{2}{21}$

д) 
$\frac{2,4*12,6*3,5}{6,3*4,8*31,5}=\frac{1*2*1}{1*2*9}=\frac{1}{9}$

е) 
$\frac{8,4*2\frac{1}{2}*12,1}{1,25*4*1,1}=\frac{2,1*2*11}{1*1*1}=2,1*22=46,2$

ж) 
$\frac{2\frac{1}{3}*1\frac{1}{7}*1\frac{1}{5}}{3\frac{3}{5}*4\frac{2}{3}*6\frac{5}{7}}=\frac{\frac{7}{3}*\frac{8}{7}*\frac{6}{5}}{\frac{18}{5}*\frac{14}{3}*\frac{47}{7}}=\frac{\frac{1}{1}*\frac{8}{1}*\frac{2}{5}}{\frac{6}{5}*\frac{2}{1}*\frac{47}{1}}=\frac{\frac{16}{5}}{\frac{12*47}{5}}=\frac{16}{5}*\frac{5}{12*47}=\frac{4}{3*47}=\frac{4}{141}$

з) 
$\frac{0,2*6,2:0,31-\frac{5}{6}*0,3}{2+1\frac{4}{11}*0,22:0,01}=\frac{0,2*6,2*\frac{100}{31}-\frac{5}{6}*\frac{3}{10}}{2+\frac{15}{11}*\frac{22}{100}*100}=\frac{0,2*0,2*100-\frac{1}{2}*\frac{1}{2}}{2+15*2}=\frac{4-\frac{1}{4}}{2+30}=\\3\frac{3}{4}:32=\frac{15}{4}*\frac{1}{32}=\frac{15}{128}$

и) 
$\frac{(1,75*\frac{2}{5}+1,75:1)1\frac{5}{7}}{(\frac{17}{40}-0,325):\frac{1}{5}*0,4}=\frac{(0,7+1,75)\frac{12}{7}}{(0,425-0,325)*5*0,4}=\frac{2,45*\frac{12}{7}}{0,1*2}=\frac{4,2}{0,2}=21$