Вычислите 1)5 5/7*9/20 2)2 1/4:1 1/8 3)-5 1/2*(-8 1/11) 4)-3 5/9*4 7/8 5)1,2+3/7 6)-0,4+5/6

Вычислим значения выражений:

1) 5 5/7 * 9/20 = (5 * 7 + 5)/7 * 9/20 = (35 + 5)/7 * 9/20 = 40/7 * 9/20 = (20 * 2 * 9)/(7 * 20) = (2 * 9)/7 = 18/7 = 2 4/7;

2) 2 1/4 : 1 1/8 = (2 * 4 + 1)/4 : (1 * 8 + 1)/8 = 9/4 : 9/8 = 9/4 * 8/9 = (9 * 4 * 2)/(4 * 9) = 2;

3) -5 1/2 * (-8 1/11) = (5 * 2 + 1)/2 * (8 * 11 + 1)/11 = 11/2 * 89/11 = 89/2 = 44 1/2;

4) -3 5/9 * 4 7/8 = -(3 * 9 + 5)/9 * (4 * 8 + 7)/8 = -32/9 * 39/8 = -(8 * 4 * 3 * 13)/(3 * 3 * 8) = -(4 * 13)/3 = -52/3 = -17 1/3;

5) 1,2 + 3/7 = 1 + 2/10 + 3/7 = 1 + 14/70 + 30/70 = 1 44/70 = 1 22/35;

6) -0,4 + 5/6 = -4/10 + 5/6 = -24/60 + 50/60 = 26/60 = 13/30.