Вычислите удобным способом:
а) 12 * 17 + 35 * 13 + 17 * 23;
б) 41 * 80 − 25 * 41 + 55 * 29;
в) 29 * 25 + 15 * 6 + 19 * 15;
г) 26 * 18 + 26 * 17 + 14 * 35.
12 * 17 + 35 * 13 + 17 * 23 = (12 * 17 + 17 * 23) + 35 * 13 = 17 * (12 + 23) + 35 * 13 = 17 * 35 + 35 * 13 = 35 * (17 + 13) = 35 * 30 = 1050
41 * 80 − 25 * 41 + 55 * 29 = 41 * (80 − 25) + 55 * 29 = 41 * 55 + 55 * 29 = 55 * (41 + 29) = 55 * 70 = 3850
29 * 25 + 15 * 6 + 19 * 15 = 29 * 25 + 15 * (6 + 19) = 29 * 25 + 15 * 25 = 25 * (29 + 15) = 25 * 44 = 25 * (40 + 4) = 25 * 40 + 25 * 4 = 1000 + 100 = 1100
26 * 18 + 26 * 17 + 14 * 35 = 26 * (18 + 17) + 14 * 35 = 26 * 35 + 14 * 35 = 35 * (26 + 14) = 35 * 40 = 1400