Répondre :

A = 6(6x-9)-(2x-3)²+4x²-9
= 18(2x-3) - (2x-3)² + (2x-3)(2x+3)
= ( 2x -3 )( 18 - 2x + 3 + 2x + 3)
A = 24(2x-3)