a, Sai

b, Đúng

c, đúng 

d, Sai

a,\(2\frac{2}{5}+1\frac{2}{5}=3\frac{2}{5}\left(S\right)\)

b,\(6\frac{3}{4}-1\frac{1}{4}=5\frac{2}{4}\left(\text{Đ}\right)\)

c,\(3\frac{1}{2}\times2\frac{2}{3}=9\frac{1}{3}\left(\text{Đ}\right)\)

d,\(4\frac{1}{6}\div2\frac{1}{5}=2\frac{5}{6}\left(S\right)\)

a,=25/6;7/6=25/6x6/7=25/7

b,=7/2x32/6=56/3

c,=17/5-11/10=34/10-11/10=23/10

d,=8/3+11/4=32/12+33/12=65/12

\(\frac{2}{3}.\frac{4}{5}+\frac{1}{3}.\frac{4}{5}=\frac{4}{5}\left(\frac{2}{3}+\frac{1}{3}\right)=\frac{4}{5}.\frac{3}{3}=\frac{4}{5}.1=\frac{4}{5}\)

\(\frac{1}{2}:\frac{3}{4}+\frac{1}{6}:\frac{3}{4}=\frac{3}{4}:\left(\frac{1}{2}+\frac{1}{6}\right)=\frac{3}{4}:\frac{2}{3}=\frac{9}{8}\)

\(\frac{2}{3}.\frac{4}{5}-\frac{1}{3}.\frac{4}{5}=\frac{4}{5}\left(\frac{2}{3}-\frac{1}{3}\right)=\frac{4}{5}.\frac{1}{3}=\frac{4}{15}\)

\(\frac{1}{2}:\frac{3}{4}-\frac{1}{6}:\frac{3}{4}=\frac{3}{4}:\left(\frac{1}{2}-\frac{1}{6}\right)=\frac{3}{4}:\frac{1}{3}=\frac{9}{4}\)

\(\frac{2}{3}.\frac{4}{5}+\frac{1}{3}.\frac{4}{5}=\left(\frac{2}{3}+\frac{1}{3}\right).\frac{4}{5}=1.\frac{4}{5}=\frac{4}{5}\)

\(\frac{1}{2}:\frac{3}{4}+\frac{1}{6}:\frac{3}{4}=\frac{1}{2}.\frac{4}{3}+\frac{1}{6}.\frac{4}{3}=\left(\frac{1}{2}+\frac{1}{6}\right).\frac{4}{3}=\frac{2}{3}.\frac{4}{3}=\frac{8}{9}\)

c,d tương tự 

\(a.1\frac{1}{3}+2\frac{1}{2}\)

\(=\frac{4}{3}+\frac{5}{2}\)

\(=\frac{8}{6}+\frac{15}{6}\)

\(=\frac{23}{6}\)

\(b.3\frac{2}{5}-1\frac{1}{7}\)

\(=\frac{17}{5}-\frac{8}{7}\)

\(=\frac{119}{35}-\frac{40}{35}\)

\(=\frac{79}{35}\)

\(c.3\frac{1}{2}.1\frac{1}{7}\)

\(=\frac{7}{2}.\frac{8}{7}\)

\(=4\)

\(d.4\frac{1}{6}:2\frac{1}{3}\)

\(=\frac{25}{6}:\frac{7}{3}\)

\(=\frac{25}{6}.\frac{3}{7}\)

\(=\frac{25}{14}\)

a) \(\frac{1,11+0,19-12,2}{0,296+0,094}-x=\left(\frac{1}{2}+\frac{1}{3}\right):2\)

Đề đúng:

\(\frac{1,11+0,19-1,3.2^6}{0,296+0,094}-x=\left(\frac{1}{2}+\frac{1}{3}\right):2\)

\(\frac{1,3-1,3.64}{0,39}-x=\left(\frac{3}{6}+\frac{2}{6}\right).\frac{1}{2}\)

\(\frac{1,3.\left(-63\right)}{0,39}-x=\frac{5}{6}.\frac{1}{2}\)

\(\frac{-81,9}{0,39}-x=\frac{5}{12}\)

\(\left(-210\right)-x=\frac{5}{12}\)

\(x=\left(-210\right)-\frac{5}{12}\)

\(x=\frac{-2520}{12}-\frac{5}{12}\)

\(x=\frac{-2525}{12}\)

b) \(x:\left(3\frac{1}{2}-5\frac{1}{6}\right)=4\frac{1}{5}-6\frac{2}{3}\)

\(x:\left(\frac{7}{2}-\frac{31}{6}\right)=\frac{21}{5}-\frac{20}{3}\)

\(x:\left(\frac{21}{6}-\frac{31}{6}\right)=\frac{63}{15}-\frac{100}{15}\)

\(x:\frac{-10}{6}=\frac{-37}{15}\)

\(x.\frac{6}{-10}=\frac{-37}{5}\)

\(x.\frac{-6}{10}=\frac{-37}{5}\)

\(x.\frac{-3}{5}=\frac{-37}{5}\)

\(x=\frac{-37}{5}:\frac{-3}{5}\)

\(x=\frac{-37}{5}.\frac{5}{-3}\)

\(x=\frac{-37}{-3}\)

\(x=\frac{37}{3}\)

Sai đề bài

Lẽ ra câu a chỉ chia 2 thì chia 22

Sai đề bài mina-san 

a,3x-3+6x-12=5

9x-15=5

9x=20

x=20/9

b,3x-6+6x-6=6

9x-12=6

9x=18

x=2

c,4x+4+5x+10=3x+20

9x+14=3x+20

9x-3x=6

6x=6

x=1

a) 3.(x-1) + 6.(x-2) = 5

3.x - 3 + 6.x - 12 = 5

9.x - 15 = 5

9.x = 5 + 15

9.x = 20

x = \(\frac{20}{9}\)

Vậy x = \(\frac{20}{9}\)

b) 3.(x-2) + 6.(x-1) = 6

  3.x - 6 + 6.x - 6 = 6

9.x - 12 = 6

9.x = 6 + 12

9.x = 18

x = 18 : 9

x = 2

Vậy x = 2

c) 4.(x+1) + 5.(x+2) = 3.x +20

4.x +4 +5.x +10 = 3.x +20

9.x + 14 = 3.x +20

9.x - 3.x = 20 - 14

6.x = 6

x = 6 : 6

x = 1

Vậy x = 1