Bonjour ;

Exercice n° 35 .

a.

(- 7)/25 x (- 5)/8

= 7/25 x 5/8

= 5/25 x 7/8

= 1/5 x 7/8

= (1 x 7)/(5 x 8)

= 7/40 .

b.

18/(- 49) x 14/27

= - 18/49 x 14/27

= - 18/27 x 14/49

= - 2/3 x 2/7

= - (2 x 2)/(3 x 7)

= - 4/21 .

c.

45/28 x 7/(- 15)

= - 45/28 x 7/15

= - 45/15 x 7/28

= - 3/1 x 1/4

= - (3 x 1)/(1 x 4)

= - 3/4 .

d.

(- 2)/6 x (- 21)/11

= 2/6 x 21/11

= 1/3 x 21/11

= 21/3 x 1/11

= 7/1 x 1/11

= (7 x 1)/(1 x 11)

= 7/11 .

e.

21/32 x 108/49

= 21/49 x 108/32

= 3/7 x 27/8

= (3 x 27)/(7 x 8)

= 81/56 .

f.

- 26 x (- 5)/39

= 26 x 5/39

= 5 x 26/39

= 5 x 2/3

= 5/1 x 2/3

= (5 x 2)/(1 x 3)

= 10/3 .

g.

8/5 x (- 5)/21

= - 8/5 x 5/21

= - 5/5 x 8/21

= - 1 x 8/21

= - 8/21 .

h.

56/(- 5) x 30/21 x 7/10

= - 56/5 x 30/21 x 7/10

= - 56/5 x 30/10 x 7/21

= - 56/5 x 3 x 1/3

= - 56/5 x 1

= - 56/5 .