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bonjour je n arrive pas a un exercice.il faut factoriser les calculs:

a)x²-4+(x-2)(x+1) c)x²+3x+(x+3)²


b)3x²-12x+12 d)(x+1)(x+2)-(3x+6)

merci a ceux qui me répondrons.


Répondre :

Bonjour,

a)x²-4+(x-2)(x+1) = x²-2² + (x-2)(x+1) = (x-2)(x+2) + (x-2)(x+1) = (x-2)[(x+2)+(x+1)] = (x-2)(x+2+x+1) = (x-2)(2x+3)

b)3x²-12x+12 = 3(x²-4x+4)

c)x²+3x+(x+3)² = (x+3)x + (x+3)(x+3) = (x+3)[(x+3)+x] = (x+3)(2x+3)

d)(x+1)(x+2)-(3x+6) = (x+1)(x+2) - 3(x+2) = 
(x+2)[(x+1)-3] = (x+2)(x-2) = x²-4