Question

Обчисліть:
1) 19/21-2/3; 2) 51/64-9/16; 3) 22/39-11/26;
4) 17/20-13/25. СРОЧНО НАДА ПЖ.

Answer 1

Ответ:

1)

$\frac{5}{21}$

2)

$\frac{15}{64}$

3)

$\frac{11}{78}$

4)

$\frac{33}{100}$

Пошаговое объяснение:

1)

$\frac{19}{21} - \frac{2}{3} = \frac{19}{21} - \frac{7 \times 2}{7 \times 3} = \\ = \frac{19}{21} - \frac{14}{21} = \frac{19 - 14}{21} = \\ = \frac{5}{21}$

2)

$\frac{51}{64} - \frac{9}{16} = \frac{51}{64} - \frac{4 \times 9}{4 \times 16} = \\ = \frac{51}{64} - \frac{36}{64} = \\ = \frac{51 - 36}{64} = \frac{15}{64}$

3)

$\frac{22}{39} - \frac{11}{26} = \\ = \frac{2 \times 22}{2 \times 39} - \frac{3 \times 11}{3 \times 26} = \\ = \frac{44}{78} - \frac{33}{78} = \\ = \frac{44 - 33}{78} = \frac{11}{78}$

4)

$\frac{17}{20} - \frac{13}{25} = \\ = \frac{5 \times 17}{5 \times 20} - \frac{4 \times 13}{4 \times 25} = \\ = \frac{85}{100} - \frac{52}{100} = \frac{33}{100}$