Réponse:
a.
A = 4x² - 4x + 1 + (5 - x)(2x - 1)
A = (2x - 1) + (5x)(2x - 1)
A = (2x - 1)(5 - x)
B = 5x (2x - 1) + 4x² - 1
B = 5x (2x - 1) + (2x + 1)(2x - 1)
B = (2x - 1)( 5x + 2x + 1)
B = (2x - 1)(7x + 1)
b. A×B = [(2x - 1)(5 - x)(2x - 1)(7x + 1)]
= (2x -1)[(5-x)(7x+1)]
= (2x-1)(35x²+5-7x²-x)
= (2x-1)(28x² -x +5)