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Bài 2a:

Tìm x

5/3x + 2/3 = 1/4

5/3x = 1/4 - 2/3

5/3x = 3/12 - 8/12

5/3x = - 5/12

x = -5/12 : 5/3

x = -5/12 x 3/5

x = - 1/4

Vậy x = -1/ 4

Câu a:

7/10.4/9 + 3/10.4/9 - 1 7/9

= 4/9.(7/10 + 3/10) - 16/9

= 4/9 - 16/9

= - 12/9

= - 4/3

Câu b:

- 5/6 + 4/9.(5/4 - 2/3).(-3)^2 + 5/9.30%

= - 5/6 + [5/9 - 8/27].9 + 5/9.3/10

= - 5/6 + 5 - 8/3 + 1/6

= (-5/6 + 1/6) - 8/3 + 5

= - 4/6 - 8/3 + 15/3

= - 2/3 - 8/3 + 15/3

= - 10/3 + 15/3

= 5/3

a,\(\frac{7}{10}\cdot\frac{4}{9}+\frac{3}{10}\cdot\frac{4}{9}-1\frac{7}{9}\)

\(=\frac{14}{45}+\frac{2}{15}-\frac{16}{9}\)

\(=\frac{14}{45}+\frac{6}{45}-\frac{80}{45}\)

\(=\frac{-60}{45}=\frac{-4}{3}\)

b,\(\frac{-5}{6}+\frac{4}{9}\cdot\left(\frac{5}{4}-\frac{2}{3}\right)\cdot\left(-3\right)^2+\frac{5}{9}\cdot30\%\)

\(=\frac{-5}{6}+\frac{4}{9}\cdot\left(\frac{7}{12}\right)\cdot9+\frac{5}{9}\cdot\frac{3}{10}\)

\(=\frac{-5}{6}+\frac{7}{3}+\frac{1}{6}\)

\(=\frac{-5}{6}+\frac{14}{6}+\frac{1}{6}\)

=\(=\frac{10}{6}=\frac{5}{3}\)

Câu c:

1/2017.(1/3 - 7/12 + 1/4) - (6 2/3 - 1,5.2^2) :5/6

= 1/2017.(4/12 - 7/12 + 3/12) - (20/3 - 1,5x 4) : 5/6

= 1/2017.0 - (20/3 - 6) x 6/5

= 0 - (20/3 - 18/3) x 6/5

= - 2/3 x 6/5

= - 4/5

a)\(3^8:3^4+2^2.2^3\)\(=3^4+2^5\)

                                    \(=81+32\)

                                    \(=113\)

b)\(3.4^2-2.3=3.\left(4^2-3\right)\)

                          \(=3.13\)

                          \(=39\)

Học tốt nha!!!

1)1/9 x 3^x = 2187:81=27

            3^x=27:1/9=243=3⁵

            =>x=5

\(\frac{1}{9}.3^4.3^x=3^7\)

\(\Leftrightarrow3^x=3^7:\frac{1}{9}:3^4=243\)

\(\Leftrightarrow3^x=3^5\)

\(\Leftrightarrow x=5\)

Câu a:

2.(x + 2/5) + 1 1 /4 = 11/20

2x + 4/5 + 5/4 = 11/20

2x = 11/20 - 5/4 - 4/5

2x = 11/20 - 25/20 - 16/20

2x = -30/20

2x = -3/2

x = -3/2 : 2

x = - 3/4

Vậy x = - 3/4

Câu b:

x - 1 1/8 - 2/3x - 5/6x = 75%

(x - 2/3x - 5/6x) = 75% + 1 1/8

x (1 - 2/3 - 5/6) = 3/4 + 9/8

x (6/6 - 4/6 - 5/6) = 6/8 + 9/8

x.(-1/2) = 15/8

x = 15/8 : (-1/2)

x = 15/8 x (-2)

= -15/4

a) \(2.\left(x+\frac{2}{5}\right)+1\frac{1}{4}=\frac{11}{20}\)

\(2.\left(x+\frac{2}{5}\right)+\frac{5}{4}=\frac{11}{20}\)

\(2.\left(x+\frac{2}{5}\right)=\frac{-7}{10}\)

\(x+\frac{2}{5}=\frac{-7}{20}\)

\(x=\frac{-13}{20}\)

Vậy \(x=\frac{-13}{20}\)

b)\(x-1\frac{1}{8}-\frac{2}{3}x-\frac{5}{6}x=75\%\)

  \(\left(x-\frac{2}{3}x-\frac{5}{6}x\right)-\frac{9}{8}=\frac{3}{4}\)

\(\frac{-1}{2}x-\frac{9}{8}=\frac{3}{4}\)

\(\frac{-1}{2}x=\frac{15}{8}\)

\(x=\frac{-15}{4}\)

Vậy \(x=\frac{-15}{4}\)

sai

sai

đúng

sai

\(37\left(3+7\right)=3^3+7^3\)

\(37\cdot10=27+343\)

\(370=370\)(thảo mãn

=>đúng

vậy 37(3+7)=3^3+7^3