Bonjour,
(3x+1)(4x-6) = 12x² - 18x + 4x - 6
= 12x² - 14x - 6
= 2(6x²-7x-3)
Calcul du discriminant : 49 - 4*(-3x6) = 49 + 12 = 121
les deux solutions sont : (7 - 11)/12 et (7+ 11)/12
donc (3x+1)(4x-6) = 12(x+1/3)(x-3/2)
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Méthode plus simple :
(1+3x)(4x-6)
= 2(1+3x)(2x-3)
= 2(1+3x)2(x-3/2)
= 4(1+3x)(x-3/2)
=4*3(1/3+x)(x-3/2)
= 12(x+1/3)(x-3/2)
