bonjour j’ai un dm à rendre pourriez vous m’aider svp ​

Réponse :

Bonsoir

1) A(x) = 0

⇔ (2x + 3)/(x + 7) = 0

⇔ 2x + 3 = 0

⇔ x = -3/2

2) A(x) = 3

⇔ (2x + 3)/(x + 7) = 3

⇔ (2x + 3)/(x + 7) - 3 = 0

⇔ (2x + 3)/(x + 7) - 3(x + 7)/(x + 7) = 0

⇔ (2x + 3 - 3x - 21)/(x + 7) = 0

⇔ -x - 18 = 0

⇔ x = -18

3) A(x) = -2

⇔ (2x + 3)/(x + 7) = -2

⇔ (2x + 3)/(x + 7) + 2 = 0

⇔ (2x + 3)/(x + 7) + 2(x + 7)/(x + 7) = 0

⇔ (2x + 3 + 2x + 14)/(x + 7) = 0

⇔ 4x + 17 = 0

⇔ x = -17/4