bonjour, pourriez-vous m'aider en mathématique s'il vous plait merci exercice 69

Bonjour,

a.

(3 - 2/3) / (4/3 x 7)

= [(3 x 3) / (1 x 3) - 2/3] : 28/3

= (9/3 - 2/3) : 28/3

= 7/3 : 28/3

= 7/3 x 3/28

= 21/84

= (21 x 1) / (21 x 4)

= 1/4

b.

(2/3 : 5/6) - 2/5

= (2/3 x 6/5) - 2/5

= 12/15 - 2/5

= (3 x 4) / (3 x 5) - 2/5

= 4/5 - 2/5

= 2/5

c.

(- 3/4 + 1/2) / (2/5 - 5/2)

= [- 3/4 + (1 x 2) / (2 x 2)] : [(2 x 2) / (5 x 2) - (5 x 5) / (2 x 5)]

= (- 3/4 + 2/4) : (4/10 - 25/10)

= - 1/4 : - 21/10

= - 1/4 x - 10/21

= 10/84

= (2 x 5) / (2 x 42)

= 5/42.

Bonjour,

a. (3 - 2/3)/(4/3 * 7)

→ 3 - 2/3 = 9/3 - 2/3 = 7/3

→ 4/3 * 7 = 28/3

→ 7/3 ÷ 28/3 = 7/3 * 3/28 = 21/84

→ 21/84 = (21 ÷ 21) / (84 ÷ 21) = 1/4

b. (2/3 ÷ 5/6) - 2/5

→ 2/3 ÷ 5/6 = 2/3 × 6/5 = 12/15

→ 12/15 - 2/5 = 4/5 - 2/5 = 2/5

c. (-3/4 + 1/2)/(2/5 - 5/2)

→ -3/4 + 1/2 = -3/4 + -2/4 = -5/4

→ 2/5 - 5/2 = 4/10 - 25/10 = (-21)/10

→ -5/4 ÷ (-21)/10 = -5/4 × 10/(-21) = (-50)/84

→ (-50)/84 = (-50 ÷ 2) / (84 ÷ 2 ) = (-25)/42