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Meilleure réponse !
2012-05-26T20:37:28+02:00

A=(2x+3)(5x-1)

=10x²-2x+15x-3

=10x²+13x-3

 

B=(4x+1)(4x-1)+(3x+1)(3x-1)    On applique les identités remarquables

=16x²-1 + 9x² - 1 = 25x²-2

 

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

=6x²-2x-(4x²-6x+2x-3)

=6x²-2x-4x²+6x-2x+3

=2x²+2x+3

 

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

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

=2*3x

=6x