№506
1/3 - 2/3 = - (2-1)/3 = - 1/3
1/4 - 3/4 = - (3-1) /4 = - 2/4 = - 1/2
2/7 - 5/7 = - (5-2)/7 = - 3/7
7/12 - 11/12 = - (11-7) /12 = - 4/12 = - 1/3
(-8)/11 - 3/11 = - 8/11 - 3/11 = - (8+3)/11 = - 11/11 = - 1
- 5/17 - 10/17 = - (5+10)/17 = - 15/17
№507.
(-2)/7 - (-5)/7 = - 2/7 - (- 5/7) = - 2/7 + 5/7 = 3/7
(-4)/9 - (-8)/9 = - 4/9 - ( - 8/9) = - 4/9 + 8/9 = 4/9
- 1/10 - (-7)/10 = - 1/10 + 7/10 =(7-1)/10 = 6/10 = 3/5
-12/19 - 7/19 = - (12+7)/19 = - 19/19 = -1
( - 4)/5 - (-3)/5 = - 4/5 + 3/5 = - 1/5
-1/24 - 11/24 = - 12/24 = - 1/2
№513.
-7/15 + 2/15 - 1/15 = -8/15 + 2/15 = -6/15 = - 2/5
-1/6 - 5/12 - 7/24 = - 4/24 - 10/24 - 7/24 = - (4+10+7)/24 = -21/24= -7/8
- 3/13 - 5/13 + 3/26 = - 6/26 - 10/26 + 3/26 = (-16+3)/26 = - 13/26 = - 1/2
9/28 - 4/7 - 1/4 = 9/28 - 16/28 - 7/28 = (9-23)/28= -14/28= -1/2
10/27 - 5/18 + 8/9 =20/54 - 15/54 + 48/54 =(68-15)/54 = 53/54
2/5 + 1/6 + 1/15 = 12/30 + 5/30 + 2/30 = 19/30