a)=>3x=33

=>x=11

b)x²⁰⁰=x

=>x²⁰⁰-x=0

=>x(x¹⁹⁹-1)=0=>x=0 hoặc x=1

c)=>1170:(x-13)=339-300=39

=>x-13=1170:39=30

=>x=43

d)=>7x=28

=>x=4

\(3(x-9)+15=12+243:3^2\)

=> 3x - 27 + 15 = 12 + 243 : 9

=> 3x - 27 + 15 = 12 + 27

=> 3x - 27 + 15 = 39

=> 3x - 27 = 39 - 15

=> 3x - 27 = 24

=> 3x = 24 + 27

=> 3x = 51

=> x = 51 : 3 = 17

Vậy x = 17

\(1170:(x-13)=339-3\cdot10^2\)

=> 1170 : [x-13] = 339 - 3 . 100

=> 1170 : [x - 13] = 339 - 300

=> 1170 : [x-13] = 39

=> x - 13 = 30

=> x = 43

a) 3 ( x - 9 ) + 15 = 12 + 243 : 3²

3 ( x - 9 ) + 15 = 12 + 27

3 ( x - 9 ) + 15 = 39

3 ( x - 9 ) = 39 - 15

3 ( x - 9 ) = 24

x - 9 = 24 : 3

x - 9 = 8

x = 8 + 9

x = 17

Vậy x = 17

b) 1170 : ( x - 13 ) = 339 - 3 . 10²

1170 : ( x - 13 ) = 339 - 300

1170 : ( x - 13 ) = 39

x - 13 = 1170 : 39

x - 13 = 30

x = 30 + 13

x = 43

Vậy x = 43

=))

a: =>1170:(x-13)=39

=>x-13=1170/39=30

=>x=43

b: \(\Leftrightarrow x^{1000}\cdot x^{999}-x=0\)

=>\(x\left(x^{1998}-1\right)=0\)

=>\(\left[{}\begin{matrix}x=0\\x^{1998}-1=0\end{matrix}\right.\Leftrightarrow x\in\left\{0;1;-1\right\}\)

a)

\(\begin{array}{l}\left( {9x - {2^3}} \right):5 = 2\\9x - {2^3} = 2.5\\9x - 8 = 10\\9x = 18\\x = 2\end{array}\)

Vậy \(x = 2\)

b)

\(\begin{array}{l}\left[ {{3^4} - \left( {{8^2} + 14} \right):13} \right]x = {5^3} + {10^2}\\\left[ {81 - \left( {64 + 14} \right):13} \right]x = 125 + 100\\\left[ {81 - 78:13} \right]x = 125 + 100\\\left[ {81 - 6} \right]x = 225\\75x = 225\\x = 3\end{array}\)

Vậy \(x = 3\)

1170-(x-13) = 339 - 3x100

1170 - (x-13) = 339 - 300

1170-(x-13) = 39

x-13 = 1170-39

x-13 = 1131

x = 1131+13 =11 44

1170 : (x - 13) = 339 - 3 . 10²

1170 : (x -13) = 339 - 3 . 100

1170 : (x  -13) = 339 - 300

1170 : (x - 13) = 39

            x - 13 = 1170 : 39 

            x - 13 = 30

            x = 30 + 13

            x = 43

vậy x = 43

ủng hô mk nha

Bài 10:

a: 2x-3 là bội của x+1

=>\(2x-3⋮x+1\)

=>\(2x+2-5⋮x+1\)

=>\(-5⋮x+1\)

=>\(x+1\in\left\{1;-1;5;-5\right\}\)

=>\(x\in\left\{0;-2;4;-6\right\}\)

b: x-2 là ước của 3x-2

=>\(3x-2⋮x-2\)

=>\(3x-6+4⋮x-2\)

=>\(4⋮x-2\)

=>\(x-2\inƯ\left(4\right)\)

=>\(x-2\in\left\{1;-1;2;-2;4;-4\right\}\)

=>\(x\in\left\{3;1;4;0;6;-2\right\}\)

Bài 14:

a: \(4n-5⋮2n-1\)

=>\(4n-2-3⋮2n-1\)

=>\(-3⋮2n-1\)

=>\(2n-1\inƯ\left(-3\right)\)

=>\(2n-1\in\left\{1;-1;3;-3\right\}\)

=>\(2n\in\left\{2;0;4;-2\right\}\)

=>\(n\in\left\{1;0;2;-1\right\}\)

mà n>=0

nên \(n\in\left\{1;0;2\right\}\)

b: \(n^2+3n+1⋮n+1\)

=>\(n^2+n+2n+2-1⋮n+1\)

=>\(n\left(n+1\right)+2\left(n+1\right)-1⋮n+1\)

=>\(-1⋮n+1\)

=>\(n+1\in\left\{1;-1\right\}\)

=>\(n\in\left\{0;-2\right\}\)

mà n là số tự nhiên

nên n=0

Bài 16:

a: \(\left(x+5\right)\left(y-3\right)=15\)

=>\(\left(x+5\right)\left(y-3\right)=1\cdot15=15\cdot1=\left(-1\right)\cdot\left(-15\right)=\left(-15\right)\cdot\left(-1\right)=3\cdot5=5\cdot3=\left(-3\right)\cdot\left(-5\right)=\left(-5\right)\cdot\left(-3\right)\)

=>\(\left(x+5;y-3\right)\in\left\{\left(1;15\right);\left(15;1\right);\left(-1;-15\right);\left(-15;-1\right);\left(3;5\right);\left(5;3\right);\left(-3;-5\right);\left(-5;-3\right)\right\}\)

=>\(\left(x,y\right)\in\left\{\left(-4;18\right);\left(10;4\right);\left(-6;-12\right);\left(-20;2\right);\left(-2;8\right);\left(0;6\right);\left(-8;-2\right);\left(-10;0\right)\right\}\)

mà (x,y) là cặp số tự nhiên

nên \(\left(x,y\right)\in\left\{\left(10;4\right);\left(0;6\right)\right\}\)

b: x là số tự nhiên

=>2x-1 lẻ và 2x-1>=-1

\(\left(2x-1\right)\left(y+2\right)=24\)

mà 2x-1>=-1 và 2x-1 lẻ

nên \(\left(2x-1\right)\cdot\left(y+2\right)=\left(-1\right)\cdot\left(-24\right)=1\cdot24=3\cdot8\)

=>\(\left(2x-1;y+2\right)\in\left\{\left(-1;-24\right);\left(1;24\right);\left(3;8\right)\right\}\)

=>\(\left(2x;y\right)\in\left\{\left(0;-26\right);\left(2;22\right);\left(4;6\right)\right\}\)

=>\(\left(x;y\right)\in\left\{\left(0;-26\right);\left(1;11\right);\left(2;6\right)\right\}\)

mà (x,y) là cặp số tự nhiên

nên \(\left(x,y\right)\in\left\{\left(1;11\right);\left(2;6\right)\right\}\)

c:

x,y là các số tự nhiên

=>x+3>=3 và y+2>=2

xy+2x+3y=0

=>\(xy+2x+3y+6=6\)

=>\(x\left(y+2\right)+3\left(y+2\right)=6\)

=>\(\left(x+3\right)\left(y+2\right)=6\)

mà x+3>=3 và y+2>=2

nên \(\left(x+3\right)\cdot\left(y+2\right)=3\cdot2\)

=>x=0 và y=0

d: xy+x+y=30

=>\(xy+x+y+1=31\)

=>\(x\left(y+1\right)+\left(y+1\right)=31\)

=>\(\left(x+1\right)\left(y+1\right)=31\)

\(\Leftrightarrow\left(x+1\right)\cdot\left(y+1\right)=1\cdot31=31\cdot1=\left(-1\right)\cdot\left(-31\right)=\left(-31\right)\cdot\left(-1\right)\)

=>\(\left(x+1;y+1\right)\in\left\{\left(1;31\right);\left(31;1\right);\left(-1;-31\right);\left(-31;-1\right)\right\}\)

=>\(\left(x,y\right)\in\left\{\left(0;30\right);\left(30;0\right);\left(-2;-32\right);\left(-32;-2\right)\right\}\)

mà (x,y) là cặp số tự nhiên

nên \(\left(x,y\right)\in\left\{\left(0;30\right);\left(30;0\right)\right\}\)

Bài 1: 

a: BCNN(10;12)=60

b: BCNN(24;10)=120

c: BCNN(4;14;26)=364

d: BCNN(6;8;10)=120

1170 : ( x - 13 ) = 339 - 3 * 100

1170 : ( x - 13 ) = 39

             x - 13   = 1170 : 39 

             x - 13    = 30

                     x    = 30 + 13 

                     x     = 43 .

a) 150- x = -9

x = 150 -(-9)

x=150+9

x=159

b)4 (x-3)=48

x-3=48÷4

x-3=12

x=12+3

x=15