Réponse :
P(x) = 4x^3 - ax^2 - (a + 2)x+6 / (x+2)
-4X^3-8x² 4X²-(a+8)x+(a+14)
----------------------------
-(a+8)x² - (a+2)x
+(a+8)x²+2(a+8)x
________________________________
(a+14) x+6
-(a+14) x-2(a+14)
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6-2a-28=0
-2a=22
a=-11
P= (X+2)(4X²+3X+3)