Réponses

2012-06-01T16:31:18+02:00

a/ 4x²-12x+9-(x-1)(3-2x)=4x²-12x+9-3x+2x²+3-2x

                                     =6x²-17x+12

 

b/ 4x²-12x+9-(x-1)(3-2x)=(2x-3)²-(x-1)(3-2x)

 

2012-06-01T16:38:06+02:00

a) 4x²-12x+9-(x-1)(3-2x)

=4x²-12x+9-(3x-2x²-3+2x)

=4x²-12x+9-3x+2x²+3-2x

=6x²-17x+12

 

b) On a 4x²-12x+9 qui se factorise en : (3-2x)²   (car delta=3/2)

 

Donc au final on a   

 

(3-2x)²-(x-1)(3-2x)

=(3-2x)(3-2x)-(x-1)(3-2x)

=(3-2x)(3-2x-x+1)

=(3-2x)(-3x+4)