Bonsoir,
A = (2x + 1)² - (x + 3)²
A = 4x² + 4x + 1 - (x² + 6x + 9)
A = 4x² + 4x + 1 - x² - 6x - 9
A = 4x² - x² + 4x - 6x + 1 - 9
A = 3x² - 2x - 8
B = (2x + 3)² - (x - 7) (x + 7)
B = 4x² + 12x + 9 - (x² - 49)
B = 4x² + 12x + 9 - x² + 49
B = 4x² - x² + 12x + 9 + 49
B = 3x² + 21x + 49
C = (x + 2) (x - 2) - (x - 3)²
C = x² - 4 - (x² - 6x + 9)
C = x² - 4 - x² + 6x - 9
C = x² - x² + 6x - 4 - 9
C = 6x - 13
D = (x - 5)² - (2x - 7) (x - 5)
D = x² - 10x + 25 - (2x² - 10x - 7x + 35)
D = x² - 10x + 25 - 2x² + 10x + 7x - 35
D = x² - 2x² - 10x + 10x + 7x + 25 - 35
D = - x² + 7x - 10
E = (3x + 1) (x - 2) - (2x - 3)²
E = 3x² - 6x + x - 2 - (4x² - 12x + 9)
E = 3x² - 6x + x - 2 - 4x² + 12x - 9
E = 3x² - 4x² - 6x + x + 12x - 2 - 9
E = - x² + 7x - 11.
