Ответ: 11/12; 27/64
Пошаговое объяснение:
1. 6 - 1 9/12 * 3 + 3/6 * 7/21 = 11/12
1) 1 9/12 * 3 = (1*12+9)/12 * 3 = 21/12 * 3/1 = 21*3/12*1 = 21*3/4*3 = 21/4
2) 3/6 * 7/21 = 3*7/6*21 = 21/6*21 = 1/6
3) 6 - 21/4 + 1/6 = 6/1 - 21/4 + 1/6 = 6*12/12 - 21*3/4*3 + 1*2/6*2 =
= 72/12 - 63/12 + 2/12 = (72-63+2)/12 = 11/12
или
6 - 1 9/12 * 3 +3/6 * 7/21 = 6- (1*12+9)/12 *3 + 3*7/6*21 =
= 6/1 - 21/12 *3/1 + 21/6*21 = 6/1 - 21*3/12*1 + 1/6 = 6/1 - 21*3/4*3 + 1/6 =
= 6/1 - 21/4 + 1/6 = 6*12/12 - 21*3/4*3 + 1*2/6*2 = 72/12 - 63/12 +2/12 =
= (72-63+2)/12 = 11/12
2. (3/4)^3 = 3/4 * 3/4 * 3/4 = 3*3*3/4*4*4 = 27/64