bonjour
a) 1/2 ( x + 1/2)² - 1/2
= 1/2 ( x² + 2 x /2 + 1/4) - 1/2
= x²/2 + 2 x / 4 + 1/8 - 1/2
= 4 x²/ 8 + 4 x /8 + 1/8 - 4/8
= 4 x² + 4 x - 3/8 = second degré
b ) x² - ( x + 1 )²
= x²- ( x² + 2 x + 1 )
= x² - x² + 2 x + 1
= 2 x + 1
c) ( x + 2/3) ( 3 x /2 - 1 )
= 3 x²/2 - x + 6 x /6 - 2/3
= 9 x²/6 - 6 x / 6 + 6 x /6 - 4/6
= 9 x² - 4 = second degré
d) ( x + 2/5 ) ( x - 2/5 )
= x² - 4/25 ( identité remarquable ) = second degré
