Упр.852 ГДЗ Никольский Потапов 7 класс (Алгебра)
б) (28,8:13*5/7+6,6*1*1/2)/(1*1/80:1,35);
в) (6,72:3/5+1*1/8*0,8)/(4,84:4) — 6*3/8;
г) ((6*7/12-3*17/36) * 2,5 — 4*1/3:0,64)/(4:1/4-0,5).
а)
$$\frac{12{,}8\cdot 3\frac{3}{4}-4\frac{4}{11}\cdot 4{,}125}{2\frac{4}{7}: \frac{3}{35}}= \frac{12{,}8\cdot \frac{15}{4}-\frac{48}{11}\cdot 4{,}125}{\frac{18}{7}:\frac{3}{35}}$$
$$=\frac{3{,}2\cdot 15-48\cdot 0{,}375}{6\cdot 5} =\frac{48-18}{30} =\frac{30}{30}=1$$
б)
$$\frac{28{,}8:13\frac{5}{7}+6{,}6\cdot 1\frac{1}{2}}{1\frac{1}{80}:1{,}35} =\frac{28{,}8:\frac{96}{7}+6{,}6\cdot \frac{3}{2}}{\frac{81}{80}:\frac{135}{100}}$$
$$=\frac{28{,}8\cdot \frac{7}{96}+3{,}3\cdot 3}{\frac{81}{80}:\frac{27}{20}} =\frac{0{,}3\cdot 7+9{,}9}{\frac{81}{80}\cdot \frac{20}{27}} =\frac{2{,}1+9{,}9}{\frac{3}{4}}$$
$$=12\cdot \frac{4}{3}=4\cdot 4=16$$
в)
$$\frac{6{,}72: \frac{3}{5}+1\frac{1}{8}\cdot 0{,}8}{4{,}84:4}-6\frac{3}{8} =\frac{6{,}72\cdot \frac{5}{3}+\frac{9}{8}\cdot 0{,}8}{1{,}21}-6\frac{3}{8}$$
$$=\frac{2{,}24\cdot 5+9\cdot 0{,}1}{1{,}21}-6\frac{3}{8} =\frac{11{,}2+0{,}9}{1{,}21}-6\frac{3}{8}$$
$$=\frac{12{,}1}{1{,}21}-6\frac{3}{8} =10-6\frac{3}{8} =3\frac{5}{8}$$
г)
$$\frac{\left(6\frac{7}{12}-3\frac{17}{36}\right)\cdot 2{,}5-4\frac{1}{3}:0{,}64}{4:\frac{1}{4}-0{,}5} =\frac{\left(6\frac{21}{36}-3\frac{17}{36}\right)\cdot 2{,}5-\frac{13}{3}:\frac{64}{100}}{4\cdot 4-0{,}5}$$
$$=\frac{3\frac{4}{36}\cdot \frac{5}{2}-\frac{13}{3}:\frac{16}{25}}{15{,}5} =\frac{3\frac{1}{9}\cdot \frac{5}{2}-\frac{13}{3}\cdot \frac{25}{16}}{15{,}5}$$
$$=\frac{\frac{28}{9}\cdot \frac{5}{2}-\frac{13}{3}\cdot \frac{25}{16}}{15{,}5} =\frac{\frac{70}{9}-\frac{325}{48}}{15{,}5} =\frac{\frac{20}{279}}{1} =\frac{20}{279}$$
Ответ
а) $$1$$; б) $$16$$; в) $$3\frac{5}{8}$$; г) $$\frac{20}{279}$$.
