(2/3+2/7-1/14) / (-1-3/7+3/28)

=(2/3+2/7-2/28) / (-3/3-3/7+3/28)

=[2.(1/3+1/7-1/28)]/[(-3).(1/3+1/7-1/28)]

=2/-3=-2/3

\(\frac{\frac{2}{3}+\frac{2}{7}-\frac{1}{14}}{-1-\frac{3}{7}+\frac{3}{28}}\)

\(=\frac{37}{\frac{42}{-\frac{37}{28}}}\)

\(=-\frac{2}{3}\)

=28/42+12/42-3/42/-28/28-12/28+3/28=40/42-3/42/-40/28+3/28=37/42/-37/42=-2/3

\(\frac{2}{3}+\frac{2}{7}-\frac{1}{14}-1-\frac{1}{37}+\frac{3}{28}=\left(\frac{2}{7}-\frac{1}{14}+\frac{3}{28}\right)+\left(\frac{2}{3}-1\right)-\frac{1}{37}\)

\(=\left(\frac{8}{28}-\frac{2}{28}+\frac{3}{28}\right)+-\frac{1}{3}-\frac{1}{37}\)

\(=\frac{9}{28}+-\frac{1}{3}-\frac{3}{7}=\left(\frac{9}{28}-\frac{3}{7}\right)+-\frac{1}{3}=\left(\frac{9}{28}+-\frac{12}{28}\right)+-\frac{1}{3}=-\frac{3}{28}+-\frac{1}{3}=-\frac{37}{84}\)

Chúc bạn học tốt!^_^

/ là dấu gạch phân số 

hãy trả lời giúp tôi

bằng \(-\frac{2}{3}\)

nhé

bằng phân số \(\frac{-2}{3}\)nhé nhớ tích nhé

Câu a:

2/3 + 1/5.10/7

= 2/3 + 2/7

= 14/21 + 6/21

= 20/21

Câu b:

2/7 + 5/7.14/25

= 2/7 + 2/5

= 10/35 + 14/25

= 24/35

Câu c:

7/12 - 27/7.1/18

= 7/12 - 3/14

= 49/84 - 18/84

= 31/84

Câu d:

3/10.(-5/6) - 1/8

= - 1/4 - 1/8

= -2/8 - 1/8

= - 3/8