Bonsoir.
Merci de mettre une formule de politesse prochainement.
A = (3-x)(4-x)(x+5)(x+6)
A = (12-3x-4x+x²)(x+5)(x+6)
A = (12-7x+x²)(x+5)(x+6)
A = (12x+60-7x²-35x+x³+5x²)(x+6)
A = (-23x+60-7x²+x³+5x²)(x+6)
A = (-23x+60-2x²+x³)(x+6)
A = -23x²-138x+60x+360-2x³-12x²+x⁴+6x³
A = -23x²-78x+360-2x³-12x²+x⁴+6x³
A = -35x²-78x+360-2x³+x⁴+6x³
A = -35x²-78x+360+4x³+x⁴
Bonne soirée.
