a) 150 : [17 - (2x - 3)] = 350

=> 17 - (2x - 3) = \(\frac{150}{350}=\frac{3}{7}\)

=> 2x - 3 = \(17-\frac{3}{7}=\frac{116}{7}\)

=> 2x = \(\frac{116}{7}+3\)

=> 2x = \(\frac{137}{7}\)

=> x = \(\frac{137}{7}:2=\frac{137}{14}\)

b) 4 . [105 - (x - 9)] - 486 = 0

=> 4. [105 - (x - 9)] = 486

=> 105 - (x - 9) = 243/2

=> x - 9 = \(105-\frac{243}{2}=-\frac{33}{2}\)

=> x = \(-\frac{33}{2}+9=-\frac{15}{2}\)

c) 1000 - 2{600 - 4.[198 - 7.(21 - 7)]}.x = 200

=> 1000 - 2{600 - 4.[198 - 7.14]}.x = 200

=> 1000 - 2{600 - 4.[198 - 98].x = 200

=> 1000 - 2{600 - 4.100}.x = 200

=> 1000 - 2{600 -400}.x = 200

=> 1000 - 2.200.x = 200

=> 2.200.x = 800

=> 400.x = 800

=> x = 2

Câu 2 :

a) 350 : [19 - (7x - 3)]  = 350

=> 19 - (7x - 3) = 1

=> 7x - 3 = 18

=> 7x = 21

=> x = 3

b) 7.[109 - (x - 9)] - 420 = 0

=> 7.[109 - (x - 9)] = 420

=> 109 - (x - 9) = 60

=> x - 9 = 49

=> x = 49 + 9 = 58

c) 254 - 2{200 - 4.[90 - 7.(19 - 9)]}.x = 54

=> 254 - 2{200 - 4.[90 - 7.10]}.x = 54

=> 254 - 2{200 - 4[90 - 70]} . x= 54

=> 254 - 2{200 - 4.20} . x = 54

=> 254 - 2{200 - 80}.x = 54

=> 254 - 2.120 . x=  54

=> 2.120.x = 200

=> 240.x = 200

=> \(x=\frac{5}{6}\)

\(\text{a)}350:\left[19-\left(7x-3\right)\right]=350\)

\(\Rightarrow19-\left(7x-3\right)=1\)

\(\Rightarrow19-7x+3=1\)

\(\Rightarrow-7x=-21\)

\(\Rightarrow x=3\)

\(\text{b)}7.\left[109-\left(x-9\right)\right]-420=0\)

\(\Rightarrow7\left(109-x+9\right)=420\)

\(\Rightarrow118-x=60\)

\(\Rightarrow x=58\)

\(\text{c)}252-2\left\{200-4\left[90-7.\left(19-9\right)\right]\right\}.x=4\)

\(\Rightarrow2\left\{200-4\left[90-7.10\right]\right\}.x=250\)

\(\Rightarrow\left[200-4\left(90-70\right)\right].x=125\)

\(\Rightarrow\left[200-4.20\right].x=125\)

\(\Rightarrow120x=125\)

\(\Rightarrow x=\frac{125}{120}=\frac{25}{24}\)

\(\text{Xin điểm ạ}\)

350:[19-(7x-3)]=350

[19-(7x-3)]=350:350

[19-(7x-3)]=1

(7x-3)=19-1

(7x-3)=18

7x=18+3

7x=21

x=21:7

x=3

vậy x=3

7.[109-(x-19)]-420=0

7.[109-(x-19)]=0+420

7.[109-(x-19)]=420

[109-(x-19)]=420:7

[109-(x-19)]=60

(x-19)=109-60

(x-19)=49

x=49+19

x=58

vậy x=58

254-2{200-4.[90-7.(19-9)]}.x=4

254-2{200-4.[90-7.10]}.x=4

254-2{200-4.[90-70]}.x=4

254-2{200-4.20}.x=4

254-2{200-80}.x=4

254-2.120.x=4

254-240.x=4

240.x=254-4

240.x=250

x=250:240

x=25/24

vậy x=25/24

\(a,\Rightarrow x+35=103\\ \Rightarrow x=68\\ b,\Rightarrow x+7=42\\ \Rightarrow x=35\\ c,\Rightarrow x-15=9\\ \Rightarrow x=24\\ d,\Rightarrow x+23=31\\ \Rightarrow x=8\\ e,\Rightarrow18-x=6\\ \Rightarrow x=12\\ f,\Rightarrow x+14=34\\ \Rightarrow x=20\\ g,\Rightarrow2x+1=21\\ \Rightarrow x=11\\ h,\Rightarrow3\left(x+1\right)=99\\ \Rightarrow x+1=33\Rightarrow x=32\\ i,5\left(x-3\right)=25\\ \Rightarrow x-3=5\\ \Rightarrow x=8\\ j,\Rightarrow8\left(2x+7\right)=88\\ \Rightarrow2x+7=11\Rightarrow x=2\\ k,\Rightarrow5\left(x+4\right)=85\\ \Rightarrow x+4=17\\ \Rightarrow x=13\)

a) x = 2.               

b) x = 7.

c) x= 12.

d)  x= 45.

e) x = 18.

f) x  = 10.

a: 2x(x+1)-135=-200

=>2(x^2+x)=-65

=>2x^2+2x+65=0

=>x^2+x+32,5=0

=>x^2+x+0,25+32,25=0

=>(x+0,5)^2+32,25=0(vô lý)

b: 4x-5(x-1)+15=13

=>4x-5x+5=-2

=>5-x=-2

=>x=5+2=7

c: 2/3x-1/4=3/5-7/8

=>2/3x=3/5-7/8+1/4=24/40-35/40+10/40=-1/40

=>x=-1/40:2/3=-1/40*3/2=-3/80

d: 1/2(2x-3)+105/2=-137/2

=>1/2(2x-3)=-137/2-105/2=-242/2=-121

=>2x-3=-242

=>2x=-239

=>x=-239/2

Bài 1 :

\(a)x=\frac{7}{25}+\left(-\frac{1}{5}\right)\)

    \(x=\frac{2}{25}\)

\(b)x=\frac{5}{11}+\left(\frac{4}{-9}\right)\)

    \(x=\frac{1}{99}\)

Mấy câu kia dễ tự làm :>

1,a) 695- [200+ (11- 1²)]

    = 695- [200+ (11- 1)]

    = 695- [200+ 10]

    = 695- 210

    = 485

  b) (5¹⁹: 5¹⁷+ 3): 7

   = (5²+ 3): 7

   = (25+ 3): 7

   = 28: 7

   = 4

  c) 129- 5[29- (6- 1²)]

   = 129- 5[29- (6- 1)]

   = 129- 5[29- 5]

   = 129- 5. 24

   = 129- 120

   = 9

3,a) 2x- 49= 5. 3²

       2x- 49= 5. 9

      2x- 49= 45

      2x     = 45+ 49

      2x     = 94

      x       = 94: 2

      x       = 47

  c) 2^x- 15= 17

     2^x       = 17+ 15

     2^x        = 32

     2^x      = 2⁵

 => x       = 5

Câu 3b bạn tự làm nhé, xin loiosxn vì không giúp được cả bài.

CHÚC BẠN HỌC GIỎI !!!

MÌNH TÌM RA CÁCH LÀM CÂU 3b RỒI !!!

5x+ 2x= 45+ 20: 15

5x+ 2x= 45+ \(\frac{4}{3}\)

5x+ 2x= \(\frac{139}{3}\)

(5+ 2)x=\(\frac{139}{3}\)

7x       =\(\frac{139}{3}\)

x         =\(\frac{139}{3}\): 7

x         =\(\frac{139}{21}\)

CHÚC BẠN HỌC GIỎI !!!