m , Ta có : \(\left(1900-2.x\right):3-32=16\)

 \(\Leftrightarrow\frac{1900-2.x}{35}-32=16\)( Nhân hai vế với 35 ) 

 \(\Leftrightarrow1900-2.x-1120=560\)

  \(\Leftrightarrow780-2.x=560\)

 \(\Leftrightarrow-2.x=560-780\)

\(\Leftrightarrow\) \(-2.x=-220\)

 \(\Rightarrow x=110\)

Vậy x = 110

n, Ta có : \(720:\left[41-\left(2.x-5\right)\right]=2^3.5\)

             \(\Leftrightarrow720:\left(41-2.x+5\right)=8.5\)

              \(\Leftrightarrow720:\left(46-2.x\right)=40\)

              \(\Leftrightarrow\frac{720}{46-2.x}=40\)

              \(\Leftrightarrow\frac{720}{2.\left(23-x\right)}=40\)

               \(\Leftrightarrow\frac{360}{23-x}\)

               \(\Leftrightarrow360=40.\left(23-x\right)\)

               \(\Leftrightarrow9=23-x\)

               \(\Leftrightarrow x=14\)

Vậy x = 14

a: \(\frac{4^5\cdot10\cdot5^6+25^5\cdot2^8}{2^8\cdot5^4+5^7\cdot2^5}\)

\(=\frac{2^{10}\cdot2\cdot5\cdot5^6+5^{10}\cdot2^8}{2^8\cdot5^4+5^7\cdot2^5}=\frac{2^8\cdot5^7\left(2^3+3^3\right)}{2^5\cdot5^4\left(2^3+3^3\right)}\)

\(=2^3\cdot5^3=10^3=1000\)

b: \(149-\left(35:x+3\right)\cdot17=13\)

=>\(\left(35:x+3\right)\cdot17=149-13=136\)

=>35:x+3=136:17=8

=>35:x=8-3=5

=>\(x=\frac{35}{5}=7\)

c: \(121:11-\left(4x+5:3\right)=4\)

=>11-(4x+5/3)=4

=>4x+5/3=11-4=7

=>\(4x=7-\frac53=\frac{21}{3}-\frac53=\frac{16}{3}\)

=>\(x=\frac{16}{3}:4=\frac43\)

d: \(720:\left\lbrack41-\left(2x-5\right)\right\rbrack=40\)

=>\(41-\left(2x-5\right)=\frac{720}{40}=18\)

=>2x-5=41-18=23

=>2x=28

=>\(x=\frac{28}{2}=14\)

e: Sửa đề: (x+1)+(x+2)+(x+3)+...+(x+100)=5700

=>100x+(1+2+3+...+100)=5700

=>\(100x+100\cdot\frac{101}{2}=5700\)

=>x+50,5=57

=>x=57-50,5

=>x=6,5

a) 128 - 3(x + 4) = 23

             3(x + 4) = 128 -23

             3(x + 4) = 105

                x + 4  = 105 : 3

                x + 4  = 35

                x        = 35 - 4

                x        = 31

\(a.128-3\left(x+4\right)=23.\)

\(3\left(x+4\right)=128-23\)

\(3\left(x+4\right)=105\)

\(x+4=105:3=35\)

\(x=35-4=31\)

\(b.\left[\left(4x+28\right)\cdot3+55\right]:5=35\)

\(\left(4x+28\right)\cdot3+55=35\cdot5=175\)

\(\left(4x+28\right)\cdot3=175-55=120\)

\(4x+28=120:3=40\)

\(4x=40-28=12\)

\(x=12:4=3\)

720 : [41 - (2x - 5)] = 2³.5

=> 720 : [41 -(2x - 5)] = 40

=> 41 - (2x - 5) = 720 : 40

=> 41 - (2x - 5) = 18

=> 2x - 5 = 41 - 18

=> 2x - 5 = 23

=> 2x = 23 + 5

=> 2x = 28

=> x = 14

=> 41-2x+5= 720:(8.5)

=> 46-2x= 720:40

=> 46-2x= 18

=> 2x= 28

=> x=14

Vậy x=14

a: \(\left[\left(10-x\right)\cdot2+51\right]:3-2=3\)

=>\(\left[2\left(10-x\right)+51\right]:3=5\)

=>\(\left[2\left(10-x\right)+51\right]=15\)

=>\(2\left(10-x\right)=15-51=-36\)

=>10-x=-36/2=-18

=>\(x=10-\left(-18\right)=10+18=28\)

b: \(\left(x-12\right)-15=20-\left(17+x\right)\)

=>\(x-12-15=20-17-x\)

=>\(x-27=3-x\)

=>\(2x=30\)

=>\(x=\dfrac{30}{2}=15\)

c: \(720-\left[41-\left(2x-5\right)\right]=2^3\cdot5\)

=>\(720-\left[41-2x+5\right]=8\cdot5=40\)

=>\(\left[41-2x+5\right]=720-40=680\)

=>-2x+46=680

=>-2x=680-46=634

=>\(x=\dfrac{634}{-2}=-317\)

Bài 2 :

n + 5 chia hết cho n

=> 5 chia hết cho n

=> n thuộc Ư(5) = {1 ; 5}

b) 2016.(n - 3) + 11 chia hết cho n - 3

=> 11  chia hết cho n - 3

=> n - 3 thuộc Ư(11) = {1 ; 11}\

=> n = {4 ; 14}

c) n² + 2n + 3 chia hết cho n + 2

n.(n + 2) + 3 chia hết cho n + 2

=> 3 chia hết cho n + 2

=> n + 2 thuộc U(3) = {1 ; 3}

=> n = {-1 ; 1}

a) 2(x + 2) + 3x = 29

2x + 4 + 3x = 29

5x = 29 - 4 = 25

x = 5

b) 720:[41 - (2x-5)]=2³ . 5

41 - (2x - 5) = 720 : 40 = 180

2x - 5 = 41 - 180 = -139

2x = -139 + 5 = -134

x = (-134) : 2 = -67

c) (x + 1) + (x + 2) + ..... + (x + 100) = 5750

x + 1 + x + 2 + ........ + x + 100 = 5750

100x + (1 + 2 + 3 + ........... + 100) = 5750

100x + 5050 = 5750

100x = 700

x = 7