Завдання 1403 - 1500 » 1461

Знайди значення виразу: 1) –5/7 + ( – 2/21) = –(15 + 2)/21 = – 17/21; 2) –57/12 + 61/6 = 57/6 – 57/12 = (14 - 7)/12 = 7/12; 3) 13/15 – 1 = 13/15 – 15/15 = – 2/15; 4) –21/8 – (–31/4) = 31/4 – 21/8 = 11/8; 5) – 7/9 · 27/49 = – (7 ∙ 27)/(9 ∙ 49) = – 3/7; 6) –11/8 · (–11/3) = (9 ∙ 4)/(8 ∙ 3) = 3/2 = 11/2; 7) 4/15 : (–11/5) = – (4 ∙ 5)/(15 ∙ 6) = – 2/9; 8) – 12/17 : (–6) = 12/(17 ∙ 6) = 2/17.