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developper et reduire A=(3x+2)²-(x-3)²

Répondre :

A = (9x*2 + 12x + 4) - (x*2 - 6x +9)
A = 9x*2 + 12x + 4 - x*2 + 6x - 9
A = 8x*2 + 18x - 5
(3x+2)²-(x-3)²=(9x²+4+12x)-(x²+9-6x)=9x²+4+12x-x²-9+6x=8x²+18x-5
(3x+2)²-(x-3)²= (3x+2+x-3)(3x+2-x+3)=(4x-1)(2x+5)