Répondre :
(x² − 25) + (x − 5) (2x + 5) = x² − 5² + (x − 5) (2x + 5)
= (x − 5) (x + 5) + (x − 5) (2x + 5)
= (x − 5) (x + 5 + 2x + 5)
= (x − 5) (3x + 10)
car a² − b² = (a − b) (a + b)
(2x + 1)² + (2x + 1) (4x + 3) = (2x + 1) (2x + 1) + (2x + 1) (4x + 3)
= (2x + 1) (2x + 1 + 4x + 3)
= (2x + 1) (6x + 4)
= (x − 5) (x + 5) + (x − 5) (2x + 5)
= (x − 5) (x + 5 + 2x + 5)
= (x − 5) (3x + 10)
car a² − b² = (a − b) (a + b)
(2x + 1)² + (2x + 1) (4x + 3) = (2x + 1) (2x + 1) + (2x + 1) (4x + 3)
= (2x + 1) (2x + 1 + 4x + 3)
= (2x + 1) (6x + 4)