B

B

\(Ư\left(30\right)=\left\{1;2;3;5;6;10;15;30\right\}\\ \Rightarrow x=5\left(B\right)\\ B\left(8\right)=\left\{0;8;16;24;32;...\right\}\\ \Rightarrow x=24\left(B\right)\)

Câu đầu : B

Câu 2 : B

a) 40 - (x - 3) = 25

 x-3=40-25

x-3=15

x=15+3

x=18

b)7x+6=20

7x=20-6

7x=14

x=14:7

x=2

a)x=18

b)x=2 

                  tick mik nha

6^x  + 99 = 20xy

Vi tong la mot so chan va 99 la so le => so le + so le = so chan

De 6^x  la so le thi => x = 0

=> ta co : 6⁰ + 99 = 20y

 => 1 + 99 = 20y

=> 20y = 100

=> y = 100 : 20

=> y = 5

Vay x = 0; y = 5

Chuc ban hoc tot !

x = 0 ; y = 5

Chứng minh rằng ababab là bội của 3

a) (3x-15)⁷ = 0

3x-15 = 0

3x = 0+15

3x = 15

x = 15:3

x = 5

b) 4^2x-6 = 1

<=> 2x-6 = 0

2x = 0+6

2x = 6

x = 6:2

x = 3

a) (3x-15)⁷ = 0

3x-15 = 0

3x = 0+15

3x = 15

x = 15:3

x = 5

b) 4^{2x - 6} = 1

<=> 2x-6 = 0

2x = 0+6

2x = 6

x = 6:2

x = 3

Ta có: 6 = 2.3

       20 = 2² .5

      15 = 3.5

=> BCNN(6; 20; 15) = 2². 3.5 = 60

=> BC(6; 20; 15) = B(60) = {0; 60; 120; 180; 240; 300; ...} 

=> (x + 1) \(\in\){0; 60; 120; 180; 240; 300; ...}

=> x \(\in\){-1; 59; 119; 179; 239; 299; ...}

Do 0 \(\le\)x \(\le\)300

=> x \(\in\){59; 119; 179; 239; 299}

Bài 1: 

a: UCLN(12;52)=4

UC(12;52)={1;2;4}

x=3x20:5=12

<=>3.20=5x

<=>5x=60

<=>x=12

Vậy x=12

x= 12