x² - 4 = (x-2)(x+2)
(x-2)² - 9 = (x-2-3)(x-2+3) = (x-5)(x+1)
(4x+1)² - x² = (4x+1+x)(4x+1-x) = (5x+1)(3x+1)
25-x² = (5-x)(5+x)
4x² - 40x + 100 = (2x - 10)²
16 - (x+1)² = (4 - x - 1)(4 + x+1) = (3-x)(x+5)
x² + 10x + 25 = (x+5)²
4x² + 4x + 1 = (2x+1)²
x² - 6x + 9 = (x-3)²
(2x+1)² - (x--2)² = (2x+1+x-2)(2x+1-x+2) = (3x-1)(2x3)
15x - 9 = 3(5x-3)
25x - x² = x(25 - x)
x² - 49+ = (x+7)(x-7)
25 - 64x² = (5-8x)(5+8x)
4x² - 9 = (2x-3)(2x+3)
je ne suis pas certain de t'avoir rendu service. Tâche de comprendre en les refaisant.