Verified answer

bonsoir

a) x² = x   ⇒ x = √x  ou - √x

b) ( x + 3)² + x² = x² + 6 x + 9 + x² = 2 x² + 6 x + 9

c) ( x - 1) ( x - 2) ( x - 4)  = ( x² - 2 x - x + 2 ) ( x - 4)

  =  ( x² - 3 x  + 2 ) ( x - 4) = x ³ - 4 x² - 3 x² + 12 x + 2 x - 8 = x³ - 7 x² + 14 x - 8

d) 2 x² - 8 x + 15  = 2 ( x - 2)² + 7  oui mais forme canonique, tu as vu cela ?

e) ( x + 5) ( x - 3) = x² - 3 x + 5 x  - 15 = x² + 2 x - 15