Bonsoir,
A = (5 + x)(2x - 1) + 2(2x - 1)(3 + x)
A = (2x - 1)(5 + x + 6 + 2x)
A = (2x - 1)(11 + 3x)
B = 2(3 - x)(x + 2) - 3(x + 2)(4 + x)
B = (x + 2)(6 - 2x - 12 - 3x)
B = (x + 2)(-6 - 5x)
C = 3(x + 1)(7 - 2x)(2 + x)
C = (7 - 2x)(3x + 3 + 2 + x)(7 - 2x)
C = (7 - 2x)(4x + 5)