Question

1/4+2/9=? 31/115-11/185=?
3/7-1/10=? 3/8+3/14-1/28=?

Answer 1

1) 1/4+2/9=?

$\frac{1}{4}+\frac{2}{9}=\frac{9*1+2*4}{36} =\frac{9+8}{36} =\frac{17}{36}$

2) 31/115-11/185=?

$\frac{31}{115} -\frac{11}{185} =\frac{31*37+11*23}{4255} =\frac{1147-253}{4255}=\frac{894}{4255}$

3) 3/7-1/10=?

$\frac{3}{7}-\frac{1}{10}=\frac{3*10-1*7}{70} =\frac{30-7}{70} =\frac{23}{70}$

4)3/8+3/14-1/28=?

$\frac{3}{8}+\frac{3}{14}-\frac{1}{28}=\frac{3*7+3*4-1*2}{56} =\frac{21+12-2}{56} =\frac{31}{56}$

Answer 2

1)

$\frac{17}{36}$

2)

$\frac{23}{70}$

3)

$\frac{894}{4255}$

4)

$\frac{31}{56}$

Пошаговое объяснение:

1)

$\frac{1}{4} + \frac{2}{9 } = \frac{9}{36} + \frac{8}{36} = \frac{17}{36}$

2)

$\frac{3}{7} - \frac{1}{10} = \frac{30}{70} - \frac{7}{70} = \frac{23}{70}$

3)

$\frac{31}{115} - \frac{11}{185} = \frac{31 \times 37}{115 \times 37} - \frac{11 \times 23}{185 \times 23} = \frac{1147}{4255} - \frac{253}{4255} = \frac{894}{4255}$

4)

$\frac{3}{8} + \frac{3}{14} - \frac{1}{28} = \frac{21}{56} + \frac{12}{56} - \frac{2}{56} = \frac{33}{56} - \frac{2}{56} = \frac{31}{56}$