Respostas:

a) 45

b) 315

c) 56

d) 30

e) 24

Resolução:

a) mmc (5, 3, 9)

5, 3, 9 | 3

5, 1 , 3 | 3

5, 1 , 1 | 5

1 , 1 , 1 |____

| 3 × 3 × 5 = 45

b) mmc (7, 5, 9)

7, 5 , 9 | 3

7, 5 , 3 | 3

7, 5 , 1 | 5

7 , 1 , 1 | 7

1 , 1 , 1 | 3 × 3 × 5 × 7 = 315

c) mmc (7, 8, 2)

7, 8, 2 | 2

7, 4 , 1 | 2

7, 2 , 1 | 2

7 , 1 , 1 | 7

1 , 1 , 1 |_______

| 2 × 2 × 2 × 7 = 56

d) mmc (3, 5, 6)

3, 5, 6 | 2

3, 5, 3 | 3

1 , 5, 1 | 5

1 , 1 , 1 |____

| 2 × 3 × 5 = 30

e) mmc (8, 12)

8, 12 | 2

4, 6 | 2

2, 3 | 2

1, 3 | 3

1, 1 |______

| 2 × 2 × 2 × 3 = 24

espero ter ajudado :)