bonjour
x² = x faux
( x + 3)² + x² = x² + 6 x + 9 + x² = 2 x² + 6 x + 9
( x - 1) ( x - 2) ( x - 4) = ( x² - 2 x - x + 2) ( x - 4)
= ( x² - 3 x + 2) ( x - 4)
= x³ - 4 x² - 3 x² + 12 x + 2 x - 8
= x ³ - 7 x² + 14 x - 8
2 x² - 8 x + 15 = 2 x² - 8 x + 15
( x + 5) ( x - 3) = x² - 3 x + 5 x - 15 = x² + 2 x - 15