Sagot :
A = (2x+1)² - (x+3)²
A = (4x² + 4x + 1) - (x² + 6x + 9)
A = 4x² + 4x + 1 -x² - 6x - 9
A = 3x² - 2x - 8
A = (4x² + 4x + 1) - (x² + 6x + 9)
A = 4x² + 4x + 1 -x² - 6x - 9
A = 3x² - 2x - 8