Câu 8:

  x=1/5

Câu 9

a: 2

b:41/36

thực hành ra luôn mọi người

Câu 8 

3/5 : x = 3 

        x = 3/5 : 3 

        x = 1/5

Câu 9 

a) 1/5 + 4/11 + 4/5 + 7/11

= ( 1/5 + 4/5 ) + ( 4/11 + 7/11 )

= 1                  +           1 

= 2 

b) 5/6 + ( 5/9 - 1/4 ) 

  = 5/6 +    7/18

= 11/9

tách ra nha

a: \(=\dfrac{7\cdot5+3\cdot9}{45}\cdot\dfrac{2}{3}=\dfrac{62}{45}\cdot\dfrac{2}{3}=\dfrac{124}{135}\)

b: \(=\dfrac{6}{11}\cdot\dfrac{5}{7}=\dfrac{30}{77}\)

c: \(=\dfrac{7}{8}\cdot\dfrac{8-3}{9}=\dfrac{7}{8}\cdot\dfrac{5}{9}=\dfrac{35}{72}\)

yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy

\(\text{#TNam}\)

`a, (7/9+3/5) \times 2/3`

`C1:`

`=62/45 \times 2/3`

`= 124/135`

`C2:`

`= 7/9 \times 2/3 + 3/5 \times 2/3`

`= 14/27 +2/5`

`= 124/135`

`b, `

`C1:`

`= 6/11 \times 5/7`

`=`30/77`

`C2:

`= 9/11 \times 5/7-3/11 \times 5/7`

`= 45/77 -15/77`

`= 30/77`

`c,`

`C1:`

`= 7/8 \times 5/9`

`=35/72`

`C2:`

`= 7/8 \times 8/9- 7/8 \times 1/3`

`= 7/9-7/24`

`=35/72`

a ) \(-5\times\left(-x+7\right)-3\times\left(-x-5\right)=-4\times\left(12-x\right)+48\)

\(\Leftrightarrow5x-35+3x+15=-48+4x+48\)

\(\Leftrightarrow5x-3x+4x=35-15-48+48\)

\(\Leftrightarrow2x=20\)

\(\Leftrightarrow x=10\)

b ) \(-2\times\left(15-3x\right)-4\times\left(-7x+8\right)=-5-9\times\left(-2x+1\right)\)

\(\Leftrightarrow-30+6x-28x-32=-5+18x-9\)

\(\Leftrightarrow6x-28x-18x=30+32-5-9\)

\(\Leftrightarrow-40x=48\)

\(\Leftrightarrow x=-1.2\)

C,D nưã bạn

 c, 7 . ( - x - 7 ) - 5 . ( - x - 3 ) = 12 . ( 3 - x)

<=> - 7x - 49  + 5x  + 15 = 36 - 12x

<=>  - 2x + 12x = 36 - 15 + 49

<=> 10 x = 70

<=> x = 7

Vẫy  x = 7

d, 5 . ( - 3x - 7 ) - 4 . ( - 2x - 11 ) = 7 . ( 4x + 10) + 9

<=> - 15x + 8x + 44 = 28x + 70 + 9

<=> - 7x + 44 = 28x + 79

<=> - 7x - 28x = 79 - 44

<=> - 35x = 35

<=> x = - 1

Vậy x = - 1

Hc tốt

Ta có:

a) ( 45 – 5 x 9 ) x 1 x 2 x 3 x 4 x 5 x 6 x 7

= (45 – 45) x 1 x 2 x 3 x 4 x 5 x 6 x 7

= 0 x 1 x 2 x 3 x 4 x 5 x 6 x 7

= 0

b) (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 8 x 8 – 8)

= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 64 – 8)

= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x 0

= 0

c) (36 – 4 x 9) : (3 x 5 x 7 x 9 x 11)

= (36 – 36) : (3 x 5 x 7 x 9 x 11)

= 0 : (3 x 5 x 7 x 9 x 11)

= 0

d) (27 – 3 x 9) : 9 x 1 x 3 x 5 x 7

= (27 – 27) : 9 x 1 x 3 x 5 x 7

= 0 : 9 x 1 x 3 x 5 x 7

=0

a) ( 45 – 5 x 9 ) x 1 x 2 x 3 x 4 x 5 x 6 x 7

= 0 x 1 x 2 x 3 x 4 x 5 x 6 x 7

b) (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 8 x 8 – 8)

= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x 0

c) (36 – 4 x 9) : (3 x 5 x 7 x 9 x 11)

= 0 : (3 x 5 x 7 x 9 x 11)

d) (27 – 3 x 9) : 9 x 1 x 3 x 5 x 7

= 0 : 9 x 1 x 3 x 5 x 7                                                                                                                  Nếu đúng thì k cho mình nhé bạn!

a. ( 45 – 5 x 9 ) x 1 x 2 x 3 x 4 x 5 x 6 x 7

= (45 – 45) x 1 x 2 x 3 x 4 x 5 x 6 x 7

= 0 x 1 x 2 x 3 x 4 x 5 x 6 x 7

= 0

b. (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 8 x 8 – 8)

= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 64 – 8)

= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x 0

= 0

c. (36 – 4 x 9) : (3 x 5 x 7 x 9 x 11)

= (36 – 36) : (3 x 5 x 7 x 9 x 11)

= 0 : (3 x 5 x 7 x 9 x 11)

= 0

d. (27 – 3 x 9) : 9 x 1 x 3 x 5 x 7

= (27 – 27) : 9 x 1 x 3 x 5 x 7

= 0 : 9 x 1 x 3 x 5 x 7

=0

1:

a: =8/7-5/88=669/616

b: \(=1+\dfrac{2}{9}\cdot\dfrac{3}{7}-\dfrac{10}{7}=1+\dfrac{2}{21}-\dfrac{10}{7}\)

\(=\dfrac{21+2-30}{21}=\dfrac{-7}{21}=\dfrac{-1}{3}\)

c: \(=\dfrac{11}{3}-\dfrac{6}{7}+4=\dfrac{77-18+84}{21}=\dfrac{143}{21}\)

Bài 2:

a: =>9/4-x=5/11*2=10/11

=>x=9/4-10/11=59/44

b: =>2/9:x=19/21

=>x=2/9:19/21=14/57

`A=2/(1xx3)+2/(3xx5)+2/(5xx7)+2/(7xx9)+2/(9xx11)+2/(11xx13)`

`=1/1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13`

`=1/1-1/13`

`=13/13-1/13`

`=12/13`