Упр.1015 ГДЗ Никольский Потапов 5 класс (Математика)

а) 2 13/30 — (1 1/10 + 1/5); б) 2 8/15 — (1 3/10 + 2/5);
в) 4 14/45 — 1 7/15 — 3/5; г) 4 11/30 — 2 9/20 — 1/10.

а) Приведём дроби в скобках к общему знаменателю:

$$ 2\frac{13}{30}-\left(1\frac{1}{10}+\frac{1}{5}\right) =2\frac{13}{30}-\left(1\frac{1}{10}+\frac{2}{10}\right) =2\frac{13}{30}-1\frac{3}{10} $$

$$ 2\frac{13}{30}-1\frac{3}{10} =2\frac{13}{30}-1\frac{9}{30} =1\frac{4}{30} =1\frac{2}{15} $$

б)

$$ 2\frac{8}{15}-\left(1\frac{3}{10}+\frac{2}{5}\right) =2\frac{8}{15}-\left(1\frac{3}{10}+\frac{4}{10}\right) =2\frac{8}{15}-1\frac{7}{10} $$

$$ 2\frac{8}{15}-1\frac{7}{10} =2\frac{16}{30}-1\frac{21}{30} =1\frac{46}{30}-1\frac{21}{30} =\frac{25}{30} =\frac{5}{6} $$

в)

$$ 4\frac{14}{45}-1\frac{7}{15}-\frac{3}{5} =4\frac{14}{45}-1\frac{21}{45}-\frac{27}{45} $$

$$ 4\frac{14}{45}-1\frac{21}{45} =3\frac{59}{45}-\frac{27}{45} =2\frac{38}{45}-\frac{27}{45} =2\frac{11}{45} $$

г)

$$ 4\frac{11}{30}-2\frac{9}{20}-\frac{1}{10} =4\frac{22}{60}-2\frac{27}{60}-\frac{6}{60} $$

$$ 4\frac{22}{60}-2\frac{27}{60} =3\frac{82}{60}-2\frac{27}{60} =1\frac{55}{60} $$

$$ 1\frac{55}{60}-\frac{6}{60} =1\frac{49}{60} $$

Ответ

а) $$1\frac{2}{15}$$; б) $$\frac{5}{6}$$; в) $$2\frac{11}{45}$$; г) $$1\frac{49}{60}$$.