Упр.38.1 ГДЗ Мерзляк Поляков 7 класс (Алгебра)

1) 2a/b·b/8a;
2) x/yz·y^4/5x;
3) 14m^9·n^2/(7m^3 );
4) (15a^4)/b^12·b^6/(10a^2 );
5) (21c^3)/(13p^2 )·39p/(28c^2 );
6) (25a^2 c)/(64b^4 )·(77b^6)/(10ac^3 ).

1. $$\frac{2a}{b}\cdot\frac{b}{8a}=\frac{2a\cdot b}{b\cdot 8a}=\frac{2}{8}=\frac14$$
2. $$\frac{x}{yz}\cdot\frac{y^4}{5x}=\frac{x\cdot y^4}{yz\cdot 5x}=\frac{y^3}{5z}$$
3. $$14m^9\cdot\frac{n^2}{7m^3}=\frac{14m^9n^2}{7m^3}=2m^6n^2$$
4. $$\frac{15a^4}{b^{12}}\cdot\frac{b^6}{10a^2}=\frac{15a^4b^6}{b^{12}\cdot 10a^2}=\frac{3a^2}{2b^6}$$
5. $$\frac{21c^3}{13p^2}\cdot\frac{39p}{28c^2}=\frac{21c^3\cdot 39p}{13p^2\cdot 28c^2}=\frac{3c\cdot 3}{p\cdot 4}=\frac{9c}{4p}$$
6. $$\frac{25a^2c}{64b^4}\cdot\frac{77b^6}{10ac^3}=\frac{25a^2c\cdot 77b^6}{64b^4\cdot 10ac^3}=\frac{5a\cdot 77b^2}{64\cdot 2c^2}=\frac{385ab^2}{128c^2}$$

Ответ

1) $$\frac14$$; 2) $$\frac{y^3}{5z}$$; 3) $$2m^6n^2$$; 4) $$\frac{3a^2}{2b^6}$$; 5) $$\frac{9c}{4p}$$; 6) $$\frac{385ab^2}{128c^2}$$.