Упр.851 ГДЗ Никольский Потапов 7 класс (Алгебра)

Задача

б) (0,134+0,05)/(18*1/6-1*11/14-2/15*2*6/7);
в) ((0,3-3/20)*1*1/2)/((1,88+2*3/25)*1/80);
г) ((0,6+0,425-0,005)*0,01)/(30*5/9+3*4/9).

Подробный ответ

а)
$$ \frac{(4{,}5\cdot 1\tfrac{2}{3}+3{,}75)\cdot \frac{7}{135}}{\frac{5}{9}} = \frac{(4{,}5\cdot \frac{5}{3}+3{,}75)\cdot \frac{7}{135}}{\frac{5}{9}} = \frac{(7{,}5+3{,}75)\cdot \frac{7}{135}}{\frac{5}{9}} = \frac{11{,}25\cdot \frac{7}{135}}{\frac{5}{9}} $$
$$ = \frac{7}{12}\cdot \frac{9}{5} = \frac{21}{20} = 1\tfrac{1}{20}. $$
б)
$$ \frac{0{,}134+0{,}05}{18\tfrac{1}{6}-1\tfrac{11}{14}-\frac{2}{15}\cdot 2\tfrac{6}{7}} = \frac{0{,}184}{18\tfrac{1}{6}-1\tfrac{11}{14}-\frac{2}{15}\cdot \frac{20}{7}} $$
$$ = \frac{0{,}184}{18\tfrac{7}{42}-1\tfrac{33}{42}-\frac{8}{21}} = \frac{0{,}184}{16\tfrac{16}{42}-\frac{8}{21}} = \frac{0{,}184}{16\tfrac{8}{21}-\frac{8}{21}} = \frac{0{,}184}{16} $$
$$ = 0{,}0115. $$
в)
$$ \frac{(0{,}3-\frac{3}{20})\cdot 1\tfrac{1}{2}}{(1{,}88+2\cdot \frac{3}{25})\cdot \frac{1}{80}} = \frac{(\frac{3}{10}-\frac{3}{20})\cdot \frac{3}{2}}{(\frac{188}{100}+2\cdot \frac{3}{25})\cdot \frac{1}{80}} $$
$$ = \frac{\frac{3}{20}\cdot \frac{3}{2}}{(\frac{47}{25}+\frac{6}{25})\cdot \frac{1}{80}} = \frac{\frac{9}{40}}{\frac{53}{25}\cdot \frac{1}{80}} = \frac{9}{40}:\frac{53}{2000} = 4{,}5. $$
г)
$$ \frac{(0{,}6+0{,}425-0{,}005)\cdot 0{,}01}{30\cdot \frac{5}{9}+3\cdot \frac{4}{9}} = \frac{(1{,}025-0{,}005)\cdot 0{,}01}{33\tfrac{9}{9}} = \frac{1{,}02\cdot 0{,}01}{34} $$
$$ = \frac{0{,}0102}{34} = \frac{102}{340000} = \frac{3}{10000} = 0{,}0003. $$