Réponse :
Bonjour,
a) (x + 4)² ⇔ (a + b)²
= x² + 2 × x × 4 + 4²
= x² + 8x + 16 ⇔ a² + 2ab + b²
b) (x + 5)² ⇔ (a + b)²
= x² + 2 × x × 5 + 5²
= x² + 10x + 25 ⇔ a² + 2ab + b²
c) (1 + 3x)(1 – 3x) ⇔ (a + b)(a – b)
= 1² – (3x)²
= 1 – 9x² ⇔ a² – b²
d) (5 + 2x)(–2x + 5)
= (5 + 2x)(5 – 2x) ⇔ (a + b)(a – b)
= 5² – (2x)²
= 25 – 4x² ⇔ a² – b²
