1) Ta có: \(\left(\dfrac{3}{4}\cdot\dfrac{5}{97}+\dfrac{1}{9}\cdot\dfrac{13}{47}\right)\cdot\left(\dfrac{1}{5}-\dfrac{7}{25}\cdot\dfrac{5}{7}\right)\)

\(=\left(\dfrac{3}{4}\cdot\dfrac{5}{97}+\dfrac{1}{9}\cdot\dfrac{13}{47}\right)\cdot\left(\dfrac{1}{5}-\dfrac{1}{5}\right)\)

=0

2) Ta có: \(\dfrac{8}{17}\cdot\dfrac{4}{15}+\dfrac{8}{17}\cdot\dfrac{22}{15}-\dfrac{8}{15}\cdot\dfrac{9}{17}\)

\(=\dfrac{8}{17}\left(\dfrac{4}{15}+\dfrac{22}{15}-\dfrac{9}{15}\right)\)

\(=\dfrac{8}{17}\cdot\dfrac{15}{15}=\dfrac{8}{17}\)

3) Ta có: \(\dfrac{2021}{2}\cdot\dfrac{1}{3}+\dfrac{4042}{4}\cdot\dfrac{1}{5}+\dfrac{6063}{3}\cdot\dfrac{22}{15}\)

\(=\dfrac{2021}{2}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)+2021\cdot\dfrac{22}{15}\)

\(=\dfrac{2021}{2}\cdot\dfrac{8}{15}+\dfrac{2021}{2}\cdot\dfrac{44}{15}\)

\(=\dfrac{2021}{2}\cdot\dfrac{52}{15}\)

\(=\dfrac{52546}{15}\)

4) Ta có: \(\dfrac{4}{7}\cdot\dfrac{2}{13}+\dfrac{8}{13}:\dfrac{7}{4}+\dfrac{4}{7}:\dfrac{13}{2}+\dfrac{4}{7}\cdot\dfrac{1}{13}\)

\(=\dfrac{4}{7}\left(\dfrac{2}{13}+\dfrac{8}{13}+\dfrac{2}{13}+\dfrac{1}{13}\right)\)

\(=\dfrac{4}{7}\)

1) Tính biểu thức:

ban biet lam thi giai ra cho minh di

1, =4/9 x (3/7 + 2 x 4/7) - 1/9 - 3/9

= 4/9 x 1 - 1/9 - 3/9 = 0

2, = ( 22/5 x 5/22 ) x 12

= 1 x 12 = 12

thằng duc bị ngu à 

dễ còn hơn cả ăn bánh

a) 2/7 X x = 2/3 

X = 2/3 : 2/7 

X = 7/3

b) 2/5 : x = 1/3

X =  2/5 : 1/3

X = 6/5

c) x : 7/11 = 22

X = 22 x 7/11

X = 14

d) 1/2 : x = 5

X = 1/2 : 5

X = 1/10

a) x = 2/3 : 2/7

x = 7/3

vậy x =...

b) x = 2/5 : 1/3

x = 6/5

vậy x =..

c) x = 22 x 7/11

x = 14

vậy x =...

d) x = 1/2 : 5

x = 1/10

vậy x =...

a) \(\dfrac{2}{7}\times x=\dfrac{2}{3}\)

            \(x=\dfrac{2}{3}\div\dfrac{2}{7}\)

           \(x=\dfrac{7}{3}\)

b) \(\dfrac{2}{5}:x=\dfrac{1}{3}\)

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

          \(x=\dfrac{6}{5}\)

c) \(x:\dfrac{7}{11}=22\)

    \(x=22\times\dfrac{7}{11}\)

    \(x=\dfrac{154}{11}\)

   \(x=14\)

d) \(\dfrac{1}{2}:x=5\)

          \(x=\dfrac{1}{2}:5\)

          \(x=\dfrac{1}{10}\)

1) 2(x + 5) + 3(x + 7) = 41
2x + 10 + 3x + 21 = 41
5x + 31 = 41
5x = 10
x = 2
6) 7(x - 1) + 5(3 - x) = 11x - 10
7x - 7 + 15 - 5x = 11x - 10
2x + 8 = 11x - 10
-9x = -18
x = 2

2) 5(x + 6) + 2(x - 3) = 38
5x + 30 + 2x - 6 = 38
7x + 24 = 38
7x = 14
x = 2

7) 4(2 + x) + 3(x - 2) = 12
8 + 4x + 3x - 6 = 12
7x + 2 = 12
7x = 10
x = 10/7

3) 7(5 + x) + 2(x - 10) = 15
35 + 7x + 2x - 20 = 15
9x + 15 = 15
9x = 0
x = 0

8) 5(2 + x) + 4(3 - x) = 10x - 15
10 + 5x + 12 - 4x = 10x - 15
x + 22 = 10x - 15
9x = 37
x = 37/9

4) 3(x + 4) + (8 - 2x) = 22
3x + 12 + 8 - 2x = 22
x + 20 = 22
x = 2

9) 7(x - 2) + 5(3 - x) = 11x - 6
7x - 14 + 15 - 5x = 11x - 6
2x + 1 = 11x - 6
-9x = -7
x = 7/9

5) 4(x + 5) + 3(7 - x) = 49
4x + 20 + 21 - 3x = 49
x + 41 = 49
x = 8

10) 5(3 - x) + 5(x + 4) = 6 + 4x
15 - 5x + 5x + 20 = 6 + 4x
35 = 6 + 4x
4x = 29
x = 29/4

z là gì vậy bn

A ) \(=\dfrac{2\times9\times11\times2\times19\times2}{11\times19\times9}=\dfrac{8}{1}=8\)

b)\(=\dfrac{2}{5}\times\left(\dfrac{4}{7}+\dfrac{9}{7}+\dfrac{8}{7}\right)=\dfrac{2}{5}\times\dfrac{21}{7}=\dfrac{2}{5}\times3=\dfrac{6}{5}\)

(x+7)(x-9)=0

=>\(\orbr{\begin{cases}x+7=0\\x-9=0\end{cases}}\)

=>\(\orbr{\begin{cases}x=-7\\x=9\end{cases}}\)

|2x-5| -7 =22

=> |2x-5|=29

=>\(\orbr{\begin{cases}2x-5=29\\2x-5=-29\end{cases}}\)

=>\(\orbr{\begin{cases}2x=34\\2x=-24\end{cases}}\)

=>\(\orbr{\begin{cases}x=17\\x=-12\end{cases}}\)

(x-2)(5-x)=0

=>\(\orbr{\begin{cases}x-2=0\\5-x=0\end{cases}}\)

=>\(\orbr{\begin{cases}x=2\\x=5\end{cases}}\)

\(\left(x+7\right)\left(x-9\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x+7=0\\x-9=0\end{cases}\Rightarrow\orbr{\begin{cases}x=-7\\x=9\end{cases}}}\)

+) ( x + 7 ) ( x- 9 ) =0

<=> x + 7 =0 hoặc x - 9 = 0

<=> x = -7 hoặc x = 9

+) | 2x - 5 | - 7 = 22

<=> | 2x - 5 | =29

<=> 2x - 5 = 29 hoặc 2x - 5 = -29

<=> x =17 hoặc x = -12

+) ( x- 2 ) ( 5 - x ) =0

<=> x - 2 = 0 hoặc 5 - x =0

<=> x = 2 hoặc x = 5

a: \(=\dfrac{3}{5}:\dfrac{7}{5}=\dfrac{3}{5}\cdot\dfrac{5}{7}=\dfrac{3}{7}\)

b: \(=\dfrac{9}{17}\left(\dfrac{8}{5}-\dfrac{3}{5}\right)+\dfrac{8}{17}\)

=9/17+8/17=1

c: =>x-3/10=7/15*1/5=7/75

=>x=7/75+3/10=59/150

a) \(\frac{22}{7}:\left(11-x\right)+\frac{2}{3}=\frac{7}{5}\)
                \(\frac{22}{7}:\left(11-x\right)=\frac{7}{5}-\frac{2}{3}\)
                \(\frac{22}{7}:\left(11-x\right)=\frac{11}{15}\)
                                \(11-x=\frac{22}{7}:\frac{11}{15}\)
                                \(11-x=\frac{30}{7}\)
                                            \(x=11-\frac{30}{7}\)
                                            \(x=\frac{47}{7}\)
b) \(22.\left(x+1\right)-12,5=53,5\)
                     \(22.\left(x+1\right)=53,5+12,5\)
                     \(22.\left(x+1\right)=66\)
                                  \(x+1=66:22\)
                                  \(x+1=3\)
                                           \(x=3-1\)
                                           \(x=2\)
c) \(\left(x-\frac{1}{2}\right).\frac{5}{2}+\frac{1}{2}=\frac{7}{4}\)
                \(\left(x-\frac{1}{2}\right).\frac{5}{2}=\frac{7}{4}-\frac{1}{2}\)
                \(\left(x-\frac{1}{2}\right).\frac{5}{2}=\frac{5}{4}\)
                             \(x-\frac{1}{2}=\frac{5}{4}:\frac{5}{2}\)
                             \(x-\frac{1}{2}=\frac{1}{2}\)
                                         \(x=\frac{1}{2}+\frac{1}{2}\)
                                         \(x=1\)
                 
            
       
                              
                                       
                                      
                                     
                                         

a)22/7:(11-x)=7/5-2/3

            22/7:(11-x)=11/15

           11-x=22/7:11/15

11-x=30/7

     x=11-30/7

      x=47/7 

vậy x=47/7

b)22.(x+1)=53,5+12,5

22.(x+1)=66

x+1=66:2

x+1=3

x=3-1

x=2

vậy x=2

c)(x-1/2).5/2=7/4-1/2

(x-1/2).5/2=5/4

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

x-1/2=1/2

x=1/2+1/2

x=1

vậy x=1 

bạn hãy tích đúng cho mình nhé

12/5-x=1

\(a,2\left(x-1\right)+3=x+2\)

\(\Leftrightarrow2x-2+3=x+2\)

\(\Leftrightarrow2x-x=2+2-3\)

\(\Leftrightarrow x=1\)

Vậy \(S=\left\{1\right\}\)

\(b,\left(3x-7\right)\left(x+5\right)=\left(5+x\right)\left(3-2x\right)\)

\(\Leftrightarrow\left(3x-7\right)\left(x+5\right)-\left(5+x\right)\left(3-2x\right)=0\)

\(\Leftrightarrow\left(x+5\right)\left(3x-7-3+2x\right)=0\)

\(\Leftrightarrow\left(x+5\right)\left(5x-10\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+5=0\\5x-10=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-5\\x=2\end{matrix}\right.\)

Vậy \(S=\left\{-5;2\right\}\)