Dấu hiệu chia hết cho cả 3 và 9

9

10

11

12

4319

4321

4320

4322

$x\in \left\{27\right\}$

$x\in \left\{28\right\}$

$x\in \left\{21\right\}$

$x\in \left\{30\right\}$

$x\in \left\{23, 24, 25, 26, 27, 28, 29\right\}$

$x\in \left\{21,22, 23, 24, 25, 26, 29\right\}$

$x\in \left\{21, 24\right\}$

$x\in \left\{21, 22, 23, 24, 25, 26, 27, 28, 29\right\}$

x=22

x=25

x=27

Đáp án khác

$x\in \left\{21, 22, 23, 24, 25, 26\right\}$

$x\in \left\{22, 23, 24, 25, 26, 27, 28\right\}$

$x\in \left\{21, 22, 23, 24, 25, 26, 27\right\}$

$x\in \left\{21, 23, 24, 25, 26, 27\right\}$