Réponses

2012-11-11T17:22:41+01:00

(2x+1)²-(4x-5)²=4x²+4x+1-[16x²-20x+20]=4x²+4x+1-16x²+20x+20=-12x²+24x²+21

2012-11-11T17:35:06+01:00

(2x+1)²-(4x-5)²

(2x)²+2*2x*1+1²-[(4x)²-2*4x*5+5²]

4x²+4x+1-[16x²-40x+25]

4x²+4x+1-16x²+40x-25

-12x²+44x-24