a, x = 28

b, x = 1

c, x = 24

d, x = 3

a, 2.(x – 5)+7 = 77

<=> 2.(x – 5) = 70 <=> x – 5 = 35 <=> x = 40

b,  x - 1 3 - 3 5 : 3 4 + 2 . 2 3 = 14

<=> x - 1 3 - 3 + 2 4 = 14

<=>  x - 1 3 = 14 + 3 - 16 = 1

<=> x – 1 = 1 <=> x = 2

c,  1 + 2 + 2 2 + 2 3 + . . . + 2 2016 = 2 x - 1 - 1

Đặt: A = 1 + 2 + 2 2 + 2 3 + . . . + 2 2016 => 2A =  2 + 2 2 + 2 3 + . . . + 2 2017

=> 2A – A = ( 2 + 2 2 + 2 3 + . . . + 2 2017 ) – ( 1 + 2 + 2 2 + 2 3 + . . . + 2 2016 )

=> A =  2 2017 - 1

Ta có:  1 + 2 + 2 2 + 2 3 + . . . + 2 2016 = 2 x - 1 - 1 =>  2 2017 - 1 =  2 x - 1 - 1 => x = 2018

d,  5 2 x - 3 - 2 . 5 2 = 5 2 . 3

<=>  5 2 x - 3 = 5 2 . 3 + 5 2 . 2

<=>  5 2 x - 3 = 5 2 . ( 3 + 2 )

<=>  5 2 x - 3 = 5 3

<=> 2x – 3 = 3 => x = 3

a) 52x - 3 - 2 . 52 = 52 . 3

x - 3/52 - 2 = 3

x = 3 + 2 + 3/52

x = 263/52

b) 740 / (x + 10) = 102 - 2 . 13

740 / (x + 10) = 76

x + 10 = 740 / 76

x + 10 = 185/19

x = 185/19 - 10

x = -5/19

c) 65 - 4x + 2 = 20140

65 - 4x = 20140 - 2

65 - 4x = 20138

4x = 65 - 20138

4x = -20073

x = -20073/4

d) 120 + 2 . (3x - 17) = 214

60 + 3 . x - 17 = 107

20 + x - 17/3 = 107/3

20 + x = 107/3 + 17/3

20 + x = 124/3

x = 124/3 - 20

x = 64/3

e) 41 - 2x + 1 = 9

42 - 2x = 9

21 - x = 9/2

x = 21 - 9/2

x = 33/2

\(a,\Rightarrow12x-91=101\\ \Rightarrow12x=192\\ \Rightarrow x=16\\ b,\Rightarrow x:23+45=133\\ \Rightarrow x:23=88\\ \Rightarrow x=\dfrac{88}{23}\\ c,\Rightarrow\left(6x-39\right):7=3\\ \Rightarrow6x-39=21\\ \Rightarrow6x=60\\ \Rightarrow x=10\\ d,\Rightarrow3x-24=\dfrac{148}{73}\\ \Rightarrow3x=\dfrac{1900}{73}\\ \Rightarrow x=\dfrac{1900}{219}\\ e,\Rightarrow\left[{}\begin{matrix}x=0\\x=10\end{matrix}\right.\\ f,\Rightarrow\left[{}\begin{matrix}x=-1\\x=2\end{matrix}\right.\\ d,\left(9-x\right)^3=64=4^3\\ \Rightarrow9-x=4\\ \Rightarrow x=5\\ h,\Rightarrow x=27\\ i,\Rightarrow6x=312\cdot12=624\cdot6\\ \Rightarrow x=624\\ j,\Rightarrow\left(19x+104\right):14=25-42=-17\\ \Rightarrow19x+104=-238\\ \Rightarrow19x=-342\\ \Rightarrow x=-18\)

a) \(8x+56:14=60\)

\(\Rightarrow8x+4=60\)

\(\Rightarrow8x=56\)

\(\Rightarrow x=\dfrac{56}{8}\)

\(\Rightarrow x=7\)

b) Mình làm rồi nhé !

c) \(41-2^{x+1}=9\)

\(\Rightarrow2^{x+1}=41-9\)

\(\Rightarrow2^{x+1}=32\)

\(\Rightarrow2^{x+1}=2^5\)

\(\Rightarrow x+1=5\)

\(\Rightarrow x=4\)

d) \(3^{2x-4}-x^0=8\)

\(\Rightarrow3^{2x-4}-1=8\)

\(\Rightarrow3^{2x-4}=9\)

\(\Rightarrow3^{2x-4}=3^2\)

\(\Rightarrow2x-4=2\)

\(\Rightarrow2x=6\)

\(\Rightarrow x=3\)

g) \(65-4^{x+2}=2014^0\)

\(\Rightarrow65-4^{x+2}=1\)

\(\Rightarrow4^{x+2}=64\)

\(\Rightarrow4^{x+2}=4^3\)

\(\Rightarrow x+2=3\)

\(\Rightarrow x=1\)

i) \(120+2\left(4x-17\right)=214\)

\(\Rightarrow2\left(4x-17\right)=214-120\)

\(\Rightarrow2\left(4x-17\right)=94\)

\(\Rightarrow4x-17=47\)

\(\Rightarrow4x=47+17\)

\(\Rightarrow4x=64\)

\(\Rightarrow x=16\)

a: \(8x+56:14=60\)

=>8x+4=60

=>8x=60-4=56

=>x=56/8=7

b: \(5^{2x-3}-2\cdot5^2=5^2\cdot3\)

=>\(5^{2x-3}=5^2\cdot3+2\cdot5^2=5^3\)

=>2x-3=3

=>2x=6

=>x=3

c: \(41-2^{x+1}=9\)

=>\(2^{x+1}=41-9=32\)

=>x+1=5

=>x=4

d: \(3^{2x-4}-x^0=8\)

=>\(3^{2x-4}-1=8\)

=>\(3^{2x-4}=8+1=9\)

=>2x-4=2

=>2x=6

=>x=3

g: \(65-4^{x+2}=2014^0\)

=>\(65-4^{x+2}=1\)

=>\(4^{x+2}=65-1=64\)

=>x+2=3

=>x=1

i: 120+2(4x-17)=214

=>2(4x-17)=214-120=94

=>4x-17=94/2=47

=>4x=64

=>\(x=\dfrac{64}{4}=16\)

rồi ko ai giúp luôn ._.

mn giúp mình gấp T-T

A= 1; 2;3;4;5;6;7;8;9;10;11;12;13( mk ko biết đánh dấu mở ngoặc vuông

mn giúp mình với ạ cần gấp !!!!

helppppppppppppppppp mn giúp mình với

bài 1 :cho tập hợp A = { x ϵ N | 5 < x ≤ 13 }

1) A = { 6; 7; 8 }

    B = { 8; 9;10}

    C = { 11; 12;13 }

2) Tập hợp A có 9 tập hợp con

bài 2 :

1) 5871 : { 928 - [(-82)+ 247)].5}

= 5871: [928 - (165.5)]

= 5871 : (928 - 825)

= 5781: 103

= 57

2) 5^{2x - 3}- 2.5² = 5².3

52x-3 - 2.52 = 52.3

52x-3 = 2.52 + 52.3

52x-3= 52. ( 3+2 ) = 5 2 . 5 = 53

2x - 3 = 3

2x = 3 + 3

2x = 6

x = 6 : 2 =3

=> x = 3

Vậy x = 3

A,-16+23+x=-16

<=>x=-16+16-23

<=>x=-23

B,10-2(4-3x)=-4

<=>10-8+6x=-4

<=>6x=-4-10+8

<=>6x=-6

<=>x=-1

C,-12+3(-x+7)=-18

<=>-12-3x+21=-18

<=>-3x=-18+12-21

<=>-3x=-27

<=>x=9

D,24:(3x-2)=-3

<=>24/(3x-2)=-3

<=>-3(3x-2)=24

<=>3x-2=-8

<=>3x=-6

<=>x=-2

E,|x+8|-7=8

<=>|x+8|=15

<=>x+8=+-15

Chia 2 TH:

TH1:x+8=15

<=>x=7

TH2:x+8=-15

<=>x=-23

F,-45:5(-3-2x)=3

<=>-9(-3-2x)=3

<=>27+18x=3

<=>18x=-24

<=>x=-4/3

G,|x-1|=0

<=>x-1=0

<=>x=1

H,-13|x|=-26

<=>|x|=2

<=>x=+-2

a) -16 + 23 + x = -16

x = -16 + 16 - 23

x = -23

Vậy x = -23

b) 10 - 2. (4 - 3x) = -4

10 - 2 . 4 + 2. 3x = -4

10 - 8 + 6x = -4

6x = -4 - 10 + 8

6x = -6

x = (-6) : 6

x = -1

Vậy x = -1

c) -12 + 3. (-x + 7) = -18

-12 + 3. (-x) + 3. 7 = -18

-12 + (-3x) + 21 = -18

-3x = -18 + 12 - 21

-3x = -27

x = (-27) : (-3)

x = -9

Vậy x = -9

d) 24 : (3x - 2) = -3

3x - 2 = 24 : (-3)

3x - 2 = -8

3x = -8 + 2

3x = -6

x = (-6) : 3

x = -2

Vậy x = -2

e) lx + 8l - 7 = 8

lx + 8l = 8 + 7

lx + 8l = 15

\(\Rightarrow\hept{\begin{cases}x+8=15\\x=18-5\\x=13\end{cases}hay\hept{\begin{cases}x+8=-15\\x=-15-8\\x=-23\end{cases}}}\)

Vậy \(x\in\left\{13;-23\right\}\)

f) (-45) : 5. (-3 - 2x) = 3

(-9). (-3 - 2x) = 3

(-9). (-3) + 9. 2x = 3

27 + 18x = 3

18x = 3 - 27

18x = -24

x = (-24) : 18

x =\(\frac{-4}{3}\)

Vậy x =\(\frac{-4}{3}\)

g) lx - 1l = 0

\(\Rightarrow x-1=0\)

x = 0 + 1

x = 1

Vậy x = 1

h) (-13). lxl = -26

lxl = (-26) : (-13)

lxl = 2

\(\Rightarrow x=2\)

Vậy x = 2

Chúc bạn học tốt!!!