bonsoir
Aire BCEF
BC = 3 x - 2 et FB = ( 3 x - 2 ) - ( x + 4) = 3 x - 2 - x - 4 = 2 x - 6
donc aire = ( 3 x - 2 ) ( 2 x - 6 ) = 6 x² - 18 x - 4 x + 12 = 6 x² - 22 x + 12
A = ( 3 x - 2 )² - ( 3 x - 2 ) ( x + 4 )
A = 9 x² - 12 x + 4 - ( 3 x² + 12 x - 2 x - 8 )
A = 9 x² - 12 x + 4 - 3 x² - 12 x + 2 x + 8 = 6 x² - 22 x + 12
A = ( 3 x - 2 ) ( 3 x - 2 - x - 4 ) = ( 3 x - 2 ) ( 2 x - 6 )