bonjour
a. x ( x + 1 ) = x² + x
b . 2 x + ( x - 2 )² = 2 x + x² - 4 x + 4 = x² - 2 x + 4
c . ( 4 x - 1 ) ( x + 4 ) = 4 x² + 16 x - x - 4 = 4 x² + 15 x - 4
d. ( x + 1 )² - 3 x² = x² + 2 x + 1 - 3 x² = - 2 x² + 2 x + 1
e. ( 2 x + 1 )² + ( x - 1 )² = 4 x² + 4 x + 1 + x² - 2 x + 1 = 5 x² + 2 x + 2
f . ( x + 1 )² - ( x - 1 )² = ( x + 1 + x - 1 ) ( x + 1 - x + 1 ) = 2 x ( 2) = 4 x
