6x+66-14x=26

-8x=26-66=-40

x=-40/-8=5

a) x - 12 - 2x - 32 = -11

-x - 44 = -11

-x  = 33

x = -33 

a/ (x-12)-(2x+31)=-6-5

    x-12-2x-31=-11

    -x=(-11)+43

-x=32

=> x=-32

Bài 6:

\(21,251+6,058+0,749+1,042\)

\(=\left(21,251+0,749\right)+\left(6,058+1,042\right)\)

\(=22+7,1\)

\(=29,1\)

___________________

\(1,53+5,309+12,47+5,691\)

\(=\left(1,53+12,47\right)+\left(5,309+5,691\right)\)

\(=14+11\)

\(=25\)

5:

a: =>x/17=5/17

=>x=5

b; =>6+x=7/11*33=21

=>x=15

c: \(\dfrac{12+x}{43-x}=\dfrac{2}{3}\)

=>3x+36=86-2x

=>5x=50

=>x=10

d: \(\dfrac{x}{5}< \dfrac{3}{7}\)

=>x<3/7*5

=>x<15/7

f: 15/26+x/16=46/52

=>x/16=23/26-15/26=8/26=4/13

=>x=4/13*16=64/13

  \(\dfrac{26}{7}\) x \(\dfrac{11}{3}-\dfrac{26}{7}\) x \(\dfrac{2}{3}-\dfrac{6}{3}\) x \(\dfrac{26}{7}\)

\(=\dfrac{26}{7}\) x \(\left(\dfrac{11}{3}-\dfrac{2}{3}-\dfrac{6}{3}\right)\)

\(=\dfrac{26}{7}\) x \(\dfrac{3}{3}\)

\(=\dfrac{26}{7}\) x \(1=\dfrac{26}{7}\)

26/7 x 11/3 - 26/7 x 2/3 - 6/3 x 26/7

=( 11/3 - 2/3 - 6/3 ) x26/7

=      1 x 26/7

=         26 /7

Tick cho mình nha

a) 71 - (33 + x) = 26

⇔ 71 - 33 - x = 26

⇔ 38 - x = 26

⇔ x = 38 - 26

⇔ x = 12

b) (x + 73) - 26 = 76

⇔ x + 73 - 26 = 76

⇔ x + 47 = 76

⇔ x = 76 - 47

⇔ x = 29

c) 45 - (x + 9) = 6

⇔ 45 - x - 9 = 6

⇔ 36 - x = 6

⇔ x = 36 - 6

⇔ x = 30

d) 89 - (73 - x) = 20

⇔ 89 - 73 + x = 20

⇔ 16 + x = 20

⇔ x = 20 - 16

⇔ x = 4

e) (x + 7) - 25 = 13

⇔ x + 7 - 25 = 13

⇔ x - 18 = 13

⇔ x = 13 + 18

⇔ x = 31

f) 198 - (x + 4) = 120

⇔ 198 - x - 4 = 120

⇔ 194 - x = 120

⇔ x = 194 - 120

⇔ x = 74

g) 140 : (x - 8) = 7

⇔ x - 8 = 140 : 7

⇔ x - 8 = 20

⇔ x = 20 + 8

⇔ x = 28

h) 4(x + 41) = 400

⇔ x + 41 = 400 : 4

⇔ x + 41 = 100

⇔ x = 100 - 41

⇔ x = 59

i) 11(x - 9) = 77

⇔ x - 9 = 77 : 11

⇔ x - 9 = 7

⇔ x = 7 + 9

⇔ x = 16

j) 5(x - 9) = 350

⇔ x - 9 = 350 : 5

⇔ x - 9 = 70

⇔ x = 70 + 9

⇔ x = 79

k) 2x - 49 = 5.3²

⇔ 2x - 49 = 45

⇔ 2x = 45 + 49

⇔ 2x = 94

⇔ x = 94 : 2

⇔ x = 47

l) 200 - (2x + 6) = 4³

⇔ 200 - 2x - 6 = 64

⇔ 194 - 2x = 64

⇔ 2x = 194 - 64

⇔ 2x = 130

⇔ x = 130 : 2

⇔ x = 65

a) 71 - (33 + x) = 26

⇔ 33+x=71-26

⇔ 33 + x = 45

⇔ x = 45 - 33

⇔ x = 12

Vậy x=12

b) (x + 73) - 26 = 76

⇔ (x + 73) = 76+26

⇔ x + 73 = 102

⇔ x = 102-73

⇔ x = 29

Vậy x=29

c) 45 - (x + 9) = 6

⇔ x + 9 = 45 - 6

⇔ x+9 = 39

⇔ x = 39 - 9

⇔ x = 30

Vậy x=30

a)

\(\dfrac{6}{13}\cdot\dfrac{8}{7}\cdot\dfrac{-26}{3}\cdot\dfrac{-7}{8}\)

\(=\dfrac{6}{13}\cdot\dfrac{-26}{3}\cdot\dfrac{8}{7}\cdot\dfrac{-7}{8}\)

\(=-4\cdot\left(-1\right)\\ =4\)

b)

\(\dfrac{6}{11}+\dfrac{11}{3}\cdot\dfrac{3}{22}\)

\(=\dfrac{6}{11}+\dfrac{1}{2}\\ =\dfrac{12}{22}+\dfrac{11}{22}\\ =\dfrac{23}{22}\)

dấu chấm là dấu nhân

2x - 15 = -11 - ( -16 )

2x - 15 = -11 + 16 

2x - 15 = 5

2x         = 5 + 15 

2x         = 20

   x        = 20 : 1 

   x        = 10 

Vậy x = 10

7 - 2x = -37 - ( -26 )

7 - 2x = -37 + 26

7 - 2x = -11

      2x = 7 - ( - 11 )

      2x = 7+ 11

      2x = 18

        x = 18 : 2 

        x = 9

Vậy x = 9 

| x + 7 | = 9 

TH1 :

x + 7 = 9

=> x  = 9 - 7 

=> x  = 2    

TH2 :

x - 7 = -9

=> x  = -9 - 7

=> x  = - 9 + ( -7 )

=> x   = -16 

Vậy x = 2 và x = -16

Câu cuối bn tự làm nha! ^-^

2x-15=-11-(-16)

2x-15= -11+16

2x-15=5

2x=5+15

2x=20

x=20:2

x=10

*) \(-7+2x=-37-\left(-26\right)\)

⇔ \(-7+2x=-11\)

⇔ \(2x=\left(-11\right)-\left(-7\right)\)

⇔ \(2x=-4\)

⇔ \(x=\left(-4\right):2\)

⇔ \(x=-2\)

\(\text{(3x +9).(11-x ) =0}\)

⇔\(\left[{}\begin{matrix}3x+9=0\\11=x=0\end{matrix}\right.\)⇔\(\left[{}\begin{matrix}3x=-9\\x=11\end{matrix}\right.\)⇔\(\left[{}\begin{matrix}x=-3\\x=11\end{matrix}\right.\)

Vậy x= -3 và x= 11