Bonjour
P = (2x - 1)² - 16
1.
x = 1/2
P = (2 * 1/2 - 1)² - 16
P = 0 - 16
P = - 16
2.
Développer et réduire P
P = (2x - 1)² - 16
P = (2x - 1) (2x - 1) - 16
P = 4x² + 2x - 2x + 1 - 16
P = 4x² - 15
3.
Factoriser P
P = (2x - 1)² - 16
P = (2x - 1 - 16) (2x + 1 + 16)
P = (2x - 15) (2x + 17)