Bonjour
1)
A = (x - 3)² + (x - 3) (1 - 2x)
A = x² - 6x + 9 + x - 2x² - 3 + 6x
A = x² - 2x² - 6x + 6x + x - 3 + 9
A = - x² + x + 6
2)
A = (x - 3)² + (x - 3) (1 - 2x)
A = (x - 3) (x - 3 + 1 - 2x)
A = (x - 3) (- x - 2)
3)
A = - x² + x + 6
A = - (- 2)² - 2 + 6
A = - 4 - 2 + 6
A = - 6 + 6
A = 0.
