Найдите значение выражения:
а) 8 * 28 + 48 * 7;
б) 38 * 150 − 45 * 80;
в) 24 * 9 + 12 * 27;
г) 46 * 75 − 65 * 30.
8 * 28 + 48 * 7 = 8 * 2 * 14 + 16 * 3 * 7 = 16 * 14 + 16 * 21 = 16 * (14 + 21) = 16 * 35 = 16 * (30 + 5) = 16 * 30 + 16 * 5 = 480 + 80 = 560
38 * 150 − 45 * 80 = 2 * 19 * 3 * 5 * 10 − 3 * 3 * 5 * 2 * 4 * 10 = (2 * 3 * 5 * 10) * 19 − (2 * 3 * 5 * 10) * 3 * 4 = 300 * (19 − 12) = 300 * 7 = 2100
24 * 9 + 12 * 27 = (4 * 6) * 9 + (2 * 6) * 27 = 4 * (6 * 9) + 6 * (2 * 27) = 4 * 54 + 6 * 54 = 54 * (4 + 6) = 540
46 * 75 − 65 * 30 = 23 * 2 * 75 − 13 * 5 * 30 = 23 * 150 − 13 * 150 = 150 * (23 − 13) = 1500