Выполните действие : а) 1/4 1/5 б)1/3 1/7 В)3/5 3/4 Г)1/2 7/9 д)5/7 0 е) 2/3-2/5 ж)1/2-1/3 з)3/5-4/7 и)5/7-1/6 к)8/9-0

Выполним действия:а) 1/4 + 1/5 = (1 * 5 + 1 * 4)/20 = (5 + 4)/20 = 9/20;б) 1/3 + 1/7 = (1 * 7 + 1 * 3)/21 = (7 + 3)/21 = 10/21;В) 3/5 + 3/4 = (3 * 4 + 3 * 5)/20 = (12 + 15)/20 = 27/20 = 1 7/20; Г) 1/2 + 7/9 = (1 * 9 + 7 * 2)/18 = (9 + 14)/20 = 23/20 = 1 3/20; д) 5/7 + 0 = 5/7; е) 2/3 - 2/5 = (2 * 5 - 2 * 3)/15 =(10 - 7)/15 = 3/15; ж) 1/2 - 1/3 = (1 * 3 - 1 * 2)/6 = (3 - 2)/6 = 1/6; з) 3/5 - 4/7 = (3 * 7 - 4 * 5)/35 = (21 - 20)/35 = 1/35; и) 5/7 - 1/6 = (5 * 6 - 1 * 7)/42 = (30 - 7)/42 = 28/42 = 14/21 = 2/3; к) 8/9 - 0 = 8/9; л) 3/4 + 4/5 = (3 * 5 + 4 * 4)/20 = (15 + 16)/20 = 31/20 = 1 11/20; м) 3/4 + 2/9 = (3 * 9 + 2 * 4)/36 = (27 + 8)/36 = 35/36.