Bonsoir,
x² + 6x + 9
= (x)² + (2)(3)(x) + (3)²
= (x + 3)²
36x² - 25
= (6x)² - (5)²
= (6x - 5)(6x + 5)
9x² - 12x + 4
= (3x)² - (2)(2)(3x) + (2)²
= (3x - 2)²
49x² - 49
= (7x)² - (7)²
= (7x - 7)(7x + 7)
100 - 40x + 4x²
= (10)² - (2)(10)(2x) + (2x)²
= (10 - 2x)²
