1) приведите дроби к общему знаменателю и выполните действия 1\2+1\4, 2\3+1\6, 5\8+5\24, 1\2-1\8 ,,2\3-4\9 3\4-1\12 2)

Задание 1.

1/2 + 1/4 = 1 · 2/2 · 2 + 1/4 = 2/4 + 1/4 = 3/4;

2/3 + 1/6 = 2 · 2/3 · 2 + 1/6 = 4/6 + 1/6 = 5/6;

5/8 + 5/24 = 5 · 3/8 · 3 + 5/24 = 15/24 + 5/24 = 20/24 = 5/6;

1/2 - 1/8 = 1 · 4/ 2 · 4 - 1/8 = 4/8 - 1/8 = 3/8;

2/3 - 4/9 = 2 · 3/3 · 3 - 4/9 = 6/9 - 4/9 = 2/9;

3/4 - 1/12 = 3 · 3/4 · 3 - 1/12 = 9/12 - 1/12 = 8/12 = 2/3.

Задание 2.

1/2 - 1/4 + 2/5 = 1 · 10/2 · 10 - 1 · 5/4 · 5 + 2 · 4/5 · 4 = 10/20 - 5/20 + 8/20 =

13/20;

3/4 - 1/2 + 7/8 = 3 · 2/4 · 2 - 1 · 4/2 · 4 + 7/8 = 6/8 - 4/8 + 7/8 = 9/8;

1/3 - 1/9 + 1/6 = 1 · 6/3 · 6 - 1 · 2/9 · 2 + 1 · 3/6 · 3 = 6/18 - 2/18 + 3/18 = 7/18;

5/6 - 2/3 + 1/4 = 5 · 2/6 · 2 - 2 · 4/3 · 4 + 1 · 3/4 · 3 = 10/12 - 8/12 + 3/12 = 5/12.

Задание 3.

1. 1/2 + х = 5/6;

х = 5/6 - 1/2 = 5/6 - 1 · 3/2 · 3 = 5/6 - 3/6;

х = 2/6 = 1/3.

2. а + 1/4 = 3/4;

а = 3/4 - 1/4;

а = 2/4 = 1/2.

3. у - 1/5 = 3/10;

у = 3/10 + 1/5 = 3/10 + 1 · 2/5 · 2 = 3/10 + 2/10;

у = 5/10 = 1/2.

4. 5/6 - с = 1/3;

с = 5/6 - 1/3 = 5/6 - 1 · 2/3 · 2 = 5/6 - 2/6;

с = 3/6 = 1/2.