bonsoir
A = ( 2 x + 3 )² - ( 4 x - 1 )²
A= 4 x² + 12 x + 9 - ( 16 x² - 8 x + 1 )
⇔ 4 x² + 12 x + 9 - 16 x² + 8 x - 1
⇔ - 12 x² + 20 x + 8
A = ( 2 x + 3 + 4 x - 1 ) ( 2 x + 3 - 4 x + 1 )
⇔ ( 6 x + 2 ) ( - 2 x + 4 )
si x = - 5
A = ( - 30 + 2 ) ( 10 + 4 ) = - 28 * 14 = - 392
bonne soirée