Bonjour,
1)
Pour x = 0
U = x² - 4x² + 3
U = 0² - 4 * 0² + 3
U = 3
V = (3 - x) (x + 1)
V = (3 - 0) (0 + 1)
V = 3 * 1
V = 3
Pour x = 3
U = x² - 4x² + 3
U = 3² - 4 * 3² + 3
U = 9 - 4 * 9 + 3
U = 9 - 36 + 3
U = 12 - 36
U = 24
V = (3 - x) (x + 1)
V = (3 - 3) (x + 1)
V = 0 * (3 + 4)
V = 0
2) Non U ≠ V
U = x² - 4x² + 3
V = (3 - x) (x + 1)
V = 3x + 3 - x² - x
V = - x² + 2x + 3