Bonsoir,
A= (2x-3) (2x+3)
A = 4x² + 6x - 6x - 9
A = 4x² - 9
B= (x+1)² + 7x (2-x)
B = x² + 2x + 1 + 14x - 7x²
B = x² - 7x² + 2x + 14x + 1
B = - 6x² + 16x + 1
C= (x+3) (2x-1) -3x (2x+5)
C = 2x² - x + 6x - 3 - 6x² - 15x
C = 2x² - 6x² - x - 15x + 6x - 3
C = - 4x² - 10x - 3
D= (4t+1) (4t-1) - (3t+2)²
D = 16t² - 4t + 4t - 1 - (9t² + 12t + 4)
D = 16t² - 1 - 9t² - 12t - 4
D = 16t² - 9t² - 12t - 1 - 4
D = 7t² - 12t - 5.