Bonsoir,
1) f(x) = 2(4x² - 1) - (2x - 1)²
f(x) = 8x² - 2 - [(2x)² - 2 (2x × 1) + 1²]
f(x) = 8x² - 2 - [4x² - 4x + 1]
f(x) = 8x² - 2 - 4x² + 4x - 1
f(x) = 4x² + 4x - 3
2) f(1/2) = 4 × (1/2)² + 4 × (1/2) - 3
f(1/2) = 1 + 2 - 3 = 3 - 3 = 0
3) forme factorisée :
f(x) = (2x - 1)(2x + 3)
Bonne soirée !
