Завдання 1201 - 1300 » 1220

Обчисли: 1) – 9/14 · 21/3 + (–5/6) · 33/4 = – (9 ∙ 7)/(14 ∙ 3) + (–(5 ∙ 15)/(6 ∙ 4)) = – 3/2 + (–25/8) = –11/2 + (–31/8) = –4(4 + 1)/8 = –45/8; 2) (15/9 · (–21/7) + 17/12) · (–11/7); 1) 15/9 · (–21/7) = – (14 ∙15)/(9 ∙7) = – 10/3 = –31/3; 2) –31/3 + 17/12 = –(24/3 – 17/12) = –1(16 - 7)/12 = –19/12 = –13/4; 3) –13/4 · (–11/7) = (7 ∙ 8)/(4 ∙ 7) = 2; 3) 0,9 · (0,8 · (–1/5) – 21/25) = 0,9 · (0,8) · (–0,2) – 0,84) = 0,9 · (–0,16 – 0,84) = 0,9 · (–1) = –0,9; 4) 15,3 – (–8,4) · (–7/12) – (–3,5)2 =15,3 – (84 ∙ 7)/(10 ∙ 12) – 12,25 = 3,05 – 4,9 = 3,05 + (–4,9) = –1,85.