Sagot :
4x² + 20x + 25 = (2x)² + 2(2x)(5) + (5)²
= (2x + 5)² car a² + 2ab + b² = (a + b)²
81 − 64² = (9)² − (64)²
= (9 + 64) (9 − 64) car a² − b² = (a + b) (a − b)
49x² − 42x + 9 = (7x)² − 2(7x)(3) + (3)²
= (7x − 3)² car a² − 2ab + b² = (a − b)²
= (2x + 5)² car a² + 2ab + b² = (a + b)²
81 − 64² = (9)² − (64)²
= (9 + 64) (9 − 64) car a² − b² = (a + b) (a − b)
49x² − 42x + 9 = (7x)² − 2(7x)(3) + (3)²
= (7x − 3)² car a² − 2ab + b² = (a − b)²