найти число,обратное числу:7/10;5;11/4;8/9;1/5;7 11/13;0,8;1,25.

Два числа a и b именуются оборотными, если a * b = 1; Если нам знаменито число a, то найдем значение b: b = 1/a;

1) a = 7/10; b = 1/a = 1/(7/10) = 1 * 10/7 = 10/7;

2) a = 5; b = 1/a = 1/5;

3) a = 11/4; b = 1/a = 1/(11/4) = 1 * 4/11 = 11/4;

4) a = 8/9; b = 1/a = 1/(8/9) = 1 * 9/8 = 9/8;

5) a = 1/5; b = 1/a = 1/(1/5) = 1 * 5/1 = 5;

6) a = 7 11/13; b = 1/a = 1/(7 11/13) = 1/(102/13) = 1 * 13/102 = 13/102;

7) a = 0,8; b = 1/a = 1/(0,8) = 1/(4/5) = 1 * 5/4 = 5/4;

8) a = 1,25; b = 1/a = 1/(1,25) = 1/(5/4) = 1 * 4/5 = 4/5;