Ответы
№ 510
1) (7/15 - 1/6) + 2/5 = (14/30 - 5/30) + 2/5 = 9/30 + 2/5 = 3/10 + 2/5 = 3/10 + 4/10 = 7/10 = 0,7
2) (3/8 - 1/9) + 25/36 = (27/72 - 8/72) + 25/36 = 19/72 + 25/36 = 19/72 + 50/72 = 69/72 = 23/24
3) (8/9 - 5/6) + 2/3 = (16/18 - 15/18) + 2/3 = 1/18 + 2/3 = 1/18 + 12/18 = 13/18
4) (7/8 - 13/20) + 9/10 = (35/40 - 26/40) + 9/10 = 9/40 + 9/10 = 9/40 + 36/40 = 45/40 = 9/8 = 1 1/8
5) (7/18 - 1/12) + 5/6 = (14/36 - 3/36) + 5/6 = 11/36 + 5/6 = 11/36 + 30/36 = 41/36 = 1 5/36
6) (3/4 - 8/15) + 17/20 = (45/60 - 32/60) + 17/20 = 13/60 + 17/20 = 13/50 + 51/60 = 64/60 = 1 4/60 = 1 1/15
№ 511
5 + 3
1) 1/3 + 1/5 = ------------ = 8/15
15
9 + 5
2) 1/5 + 1/9 = ------------ = 14/45
45
4 + 7
3) 1/7 + 1/4 = --------- = 11/28
28
8 + 3
4) 1/3 + 1/8 = -----------= 11/24
24
2 + 3
5) 1/3 + 1/2 = ----------- = 5/6
6
7 + 6
6) 1/6 + 1/7 = ---------- = 13/42
42