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 = 35 * 13 + 17 * (12 + 23) = 35 * 13 + 17 * 35 = 35 * (13 + 17) = 35 * 30 = 30 * (30 + 5) = 30 * 30 + 30 * 5 = 900 + 150 = 1050
41 * 80 − 25 * 41 + 55 * 29 = 41 * (80 − 25) + 55 * 29 = 41 * 55 + 55 * 29 = 55 * (41 + 29) = 55 * 70 = 70 * (50 + 5) = 70 * 50 + 70 * 5 = 3500 + 350 = 3850
29 * 25 + 15 * 6 + 19 * 15 = 15 * (6 + 19) + 29 * 25 = 15 * 25 + 29 * 25 = 25 * (15 + 29) = 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 = 40 * (30 + 5) = 40 * 30 + 40 * 5 = 1200 + 200 = 1400
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