Bonjour,
A = (3x - 1/2) (2x - 1/3)
A = 6x² - 3/3x - 2/2x + 1/6
A = 6x² - x - x + 1/6
A = 6x² - 2x + 1/6
B = (5/4x + 1) (3/2x - 1)
B = 15/8x - 5/4x + 3/2x - 1
B = 15/8x - 10/8x + 12/8x - 1
B = 17/8x - 1
C = (1/2x - 1/3) (1/3x - 1/2)
C = 1/6x - 1/4x - 1/9x + 1/6
C = 6/36x - 9/36x - 4/36x + 6/36
C = - 7/36x + 6/36.