1, 476 : x =28

               x=476 : 28

               x=17

Vậy x= 17

,2, x : 26 = 39

     x=39 . 26

     x=1014

Vậy x= 1014

Thôi nhiều quá mình không trả lời được

~Thôi chúc bạn học giỏi~

1)476:x=28

x=476:28

x=17

2)x:26=39

x=39x26

x=1014

476 : x = 68

x.          = 476 : 68 

x.          = 7

`#040911`

`a)`

`6 \times x - 5 = 613`

`=> 6 \times x = 613 + 5`

`=> 6 \times x = 618`

`=> x = 618 \div 6`

`=> x = 103`

Vậy, `x = 103`

`b)`

`12 \times x + 3 \times x = 30`

`=> x \times (12 + 3) = 30`

`=> x \times 15 = 30`

`=> x = 30 \div 15`

`=> x = 2`

Vậy, `x = 2`

`c)`

`125 - 25 \times (x - 1) = 100`

`=> 25 \times (x - 1) = 125 - 100`

`=> 25 \times (x - 1) = 25`

`=> x - 1 = 25 \div 25`

`=> x - 1 = 1`

`=> x = 1 + 1`

`=> x = 2`

Vậy, `x = 2`

`d)`

`(x - 2) \times (9x - 4) = 0?`

`=>`

TH1: `x - 2 = 0`

`=> x = 0 + 2`

`=> x = 2`

TH2: `9x - 4 = 0`

`=> 9x = 4`

`=> x = 4/9`

Vậy, `x \in {2; 4/9}.`

\(a,6x-5=613\\ \Leftrightarrow6x=618\\ \Leftrightarrow x=103\\ b,12x+3x=30\\ \Leftrightarrow15x=30\\ \Leftrightarrow x=2\\ c,125-25\left(x-1\right)=100\\ \Leftrightarrow25\left(x-1\right)=25\\ \Leftrightarrow x-1=1\\ \Leftrightarrow x=2\\ d,\left(x-2\right)\cdot\left(9x-4\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{4}{9}\end{matrix}\right.\)

Bài 3 là hỗn số hả em?

Bài 1: 

a) Ta có: \(\dfrac{2}{5}\cdot x+\dfrac{1}{3}=\dfrac{1}{5}\)

\(\Leftrightarrow\dfrac{2}{5}\cdot x=\dfrac{1}{5}-\dfrac{1}{3}=\dfrac{-2}{15}\)

\(\Leftrightarrow x=\dfrac{-2}{15}:\dfrac{2}{5}=\dfrac{-2}{15}\cdot\dfrac{5}{2}\)

hay \(x=-\dfrac{1}{3}\)

Vậy: \(x=-\dfrac{1}{3}\)

b) Ta có: \(\dfrac{1}{5}+\dfrac{5}{3}:x=\dfrac{1}{2}\)

\(\Leftrightarrow\dfrac{5}{3}:x=\dfrac{1}{2}-\dfrac{1}{5}=\dfrac{3}{10}\)

\(\Leftrightarrow x=\dfrac{5}{3}:\dfrac{3}{10}=\dfrac{5}{3}\cdot\dfrac{10}{3}\)

hay \(x=\dfrac{50}{9}\)

Vậy: \(x=\dfrac{50}{9}\)

c) Ta có: \(\dfrac{4}{9}-\dfrac{5}{3}\cdot x=-2\)

\(\Leftrightarrow\dfrac{5}{3}x=\dfrac{4}{9}+2=\dfrac{22}{9}\)

\(\Leftrightarrow x=\dfrac{22}{9}:\dfrac{5}{3}=\dfrac{22}{9}\cdot\dfrac{3}{5}\)

hay \(x=\dfrac{22}{15}\)

Vậy: \(x=\dfrac{22}{15}\)

d) Ta có: \(\dfrac{5}{7}:x-3=\dfrac{-2}{7}\)

\(\Leftrightarrow\dfrac{5}{7}:x=\dfrac{-2}{7}+3=\dfrac{19}{21}\)

\(\Leftrightarrow x=\dfrac{5}{7}:\dfrac{19}{21}=\dfrac{5}{7}\cdot\dfrac{21}{19}\)

hay \(x=\dfrac{15}{19}\)

Vậy:\(x=\dfrac{15}{19}\)

\(a,\dfrac{1}{3}+\dfrac{3}{4}\times\dfrac{2}{9}=\dfrac{1}{3}+\dfrac{6}{36}=\dfrac{1}{3}+\dfrac{1}{6}=\dfrac{2}{6}+\dfrac{1}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)

\(b,2-\left(\dfrac{2}{5}+\dfrac{2}{3}\right)=2-\left(\dfrac{6}{15}+\dfrac{10}{15}\right)=2-\dfrac{16}{15}=\dfrac{30}{15}-\dfrac{16}{15}=\dfrac{14}{15}\)

\(c,\dfrac{2}{5}:\dfrac{4}{7}+\dfrac{1}{3}=\dfrac{2}{5}\times\dfrac{7}{4}+\dfrac{1}{3}=\dfrac{14}{20}+\dfrac{1}{3}=\dfrac{7}{10}+\dfrac{1}{3}=\dfrac{21}{30}+\dfrac{10}{30}=\dfrac{31}{30}\)

\(d,\dfrac{9}{13}:\dfrac{3}{26}-\dfrac{8}{13}=\dfrac{9}{13}\times\dfrac{26}{3}-\dfrac{8}{13}=\dfrac{234}{39}-\dfrac{8}{13}=6-\dfrac{8}{13}=\dfrac{78}{13}-\dfrac{8}{13}=\dfrac{70}{13}\)

a:=1/3+6/36

=1/3+1/6

=1/2

b: =2-16/15

=14/15

c: =2/5*7/4+1/3

=14/20+1/3

=7/10+1/3

=21/30+10/30=31/30

d: =9/13*26/3-8/13

=3-8/13=31/13

Áp dụng tính chất giao hoán, ta có:

68 130 x 9 = 9 x 68 130 = 613 170                                      

5 x 613 170 = 613 170 x 5 = 3 065 850

Áp dụng tính chất kết hợp, ta có:

9 x 68 130 x 5 = 613 170 x 5 = 3 065 850                           

5 x 9 x 68 130 = 5 x (9 x 68 130) = 5 x 613 170 = 3 065 850

a: \(x\cdot\dfrac{2}{5}+\dfrac{1}{2}\cdot x=9\)

=>\(x\left(\dfrac{2}{5}+\dfrac{1}{2}\right)=9\)

=>\(x\cdot\dfrac{9}{10}=9\)

=>\(x=9:\dfrac{9}{10}=10\)

b: \(\dfrac{1}{9}:x+\dfrac{3}{9}:x=\dfrac{5}{7}\)

=>\(\left(\dfrac{1}{9}+\dfrac{3}{9}\right):x=\dfrac{5}{7}\)

=>\(\dfrac{4}{9}:x=\dfrac{5}{7}\)

=>\(x=\dfrac{4}{9}:\dfrac{5}{7}=\dfrac{4}{9}\cdot\dfrac{7}{5}=\dfrac{28}{45}\)

a) 12/5

b) 1/6

c) 6/7

d) 8/45

a) \(\dfrac{12}{5}\)

b) \(\dfrac{1}{6}\)

c) \(\dfrac{6}{7}\)

d) \(\dfrac{8}{45}\)

a) \(\dfrac{4}{5}+\dfrac{1}{3}=\dfrac{12}{15}+\dfrac{5}{15}=\dfrac{17}{15}\)

b) \(\dfrac{2}{3}:4=\dfrac{2}{3}:\dfrac{4}{1}=\dfrac{2}{3}x\dfrac{1}{4}=\dfrac{2}{12}=\dfrac{1}{6}\)

c) \(\dfrac{13}{7}-\dfrac{7}{7}=\dfrac{91}{49}-\dfrac{49}{49}=\dfrac{42}{49}=\dfrac{6}{7}\)

d) \(\dfrac{4}{9}x\dfrac{2}{5}=\dfrac{8}{45}\)