Вправи 301 - 400 » 340

Обчисліть значення виразу найзручнішим способом: 1) 35/14 ∙ 7/9 – 23/14 ∙ 7/9 = (35/14 – 23/14) ∙ 7/9 = 12/14 ∙ 7/9 = 11/7 ∙ 7/9 = 8/7 ∙ 7/9 = 8/9; 2) 71/5 ∙ 21/8 + 71/5 ∙ 15/8 = 71/5 ∙ (21/8 + 15/8) = 71/5 ∙ 36/8 = 36/5 ∙ 33/4 = 36/5 ∙ 15/4 = 9 ∙ 3 = 27; 3) 3/4 ∙ 13/5 + 13/5 ∙ 13/8 – 11/2 ∙ 13/5 = (3/4 + 13/8 – 11/2) ∙ 13/5 = (3/4 + 3/8 – 1/2) ∙ 8/5 = ((3 • 2 + 3 - 1 • 4)/8) ∙ 8/5 = 5/8 ∙ 8/5 = 1; 4) 39/14 ∙ 0,3 – 0,3 ∙ 110/21 + 0,3 ∙ 11/6 = (39/14 – 110/21 + 11/6) ∙ 3/10 = (3 + (9/14 – 10/21 + 1/6)) ∙ 3/10 = (3 + (9 • 3 - 10 • 2 + 1 • 7)/42) ∙ 3/10 = 314/42 ∙ 3/10 = 31/3 ∙ 3/10 = 10/3 ∙ 3/10 = 1.