Sai môn học r bạn ơi

a)x\(\in\left\{-5;-4;-3;-2;-1\right\}\)

b)x\(\in\left\{-2;-1;0;1;2;3\right\}\)

c)x\(\in\left\{-4;-3;-2;-1;0;1;2;3;4\right\}\)

d)x\(\in\left\{1;2;3;4\right\}\)

e)x\(\in\left\{0;1;2;3;4\right\}\)

f)x\(\in\left\{-10;-9;-8;-7\right\}\)

84/35 - 20/ 35 = 64/35

64/25

\(\dfrac{64}{35}\)

\(a,x< \dfrac{1}{6}:\dfrac{1}{3}=\dfrac{1}{6}\times3=\dfrac{1}{2}=0,5\\ \Rightarrow x=0\\ b,\dfrac{8}{5}>x>\dfrac{6}{7}\\ \Rightarrow x=1\)

\(=\dfrac{3}{7}\cdot\left(\dfrac{4}{9}+\dfrac{5}{9}+1\right)=\dfrac{3}{7}\cdot2=\dfrac{6}{7}\)

\(=\dfrac{3}{7}\times\dfrac{4}{9}\times\dfrac{5}{9}\times\dfrac{3}{7}+\dfrac{3}{7}=\dfrac{3}{7}\times\left(\dfrac{4}{9}+\dfrac{5}{9}+1\right)=\dfrac{3}{7}\times2=\dfrac{6}{7}\)

=3/7 x (4/9 + 5/9) = 3/7 x1 =3/7

\(a,\dfrac{6}{7}+\dfrac{3}{10}=\dfrac{60}{70}+\dfrac{21}{70}=\dfrac{81}{70}\\ b,\dfrac{5}{9}+\dfrac{1}{3}=\dfrac{5}{9}+\dfrac{3}{9}=\dfrac{8}{9}\\ c,\dfrac{5}{8}-\dfrac{2}{5}=\dfrac{25}{40}-\dfrac{16}{40}=\dfrac{9}{40}\\ d,\dfrac{1}{4}-\dfrac{1}{7}=\dfrac{7}{28}-\dfrac{4}{28}=\dfrac{3}{28}\)

\(a.\dfrac{6}{7}-\dfrac{4}{21}=\dfrac{18-4}{21}=\dfrac{14}{21}=\dfrac{2}{3}\\ b.6\times\dfrac{12}{18}=\dfrac{6\times12}{18}=\dfrac{4}{1}=4\\ c.\dfrac{2}{5}\times\dfrac{3}{7}+\dfrac{2}{5}\times\dfrac{4}{7}-\left(\dfrac{3}{7}+\dfrac{4}{7}\right)\times\dfrac{2}{5}=\dfrac{7}{7}\times\dfrac{2}{5}=1\times\dfrac{2}{5}=\dfrac{2}{5}\)

18/21 - 4/21 = 14/21 = 2/3

(3/7+4/7)x 2/5= 7/7x 2/5 = 1x2/5 = 2/5

a: \(x\in\left\{-4;-3;-2;-1;0;1;2;3;4\right\}\)

Tổng là 0

b: \(x\in\left\{-6;-5;-4;-3;-2;-1;0;1;2;3;4;5;6;7\right\}\)

Tổng là 7

4/9-5/18 = 8/18 - 5/18 = 3/18 = 1/6

3/5x5/7 = 3/7

4/7:2/7 = 4/7 x 7/2 = 2

4/9-5/18= 8/18 - 5/18 = 3/18 = 1/6

 3/5x5/7=15/35 = 3/7    

4/7:2/7=4/7 x 7/2 = 4/2 = 2

x+ 5=12-7

x+5=5

x=0

\(x+5=5\Leftrightarrow x=0\)

x+5=5

⇔x=0