Réponses

2012-10-07T17:06:47+02:00

2x(x-1)-[(x2-1)]=2x2-2x-x2+1=x2-2x+1/(x+1)2=(x-1)2/(x+1)2

2012-10-07T17:39:01+02:00

2x-1/x+1 est sous la forme u/v

Donc d'(x)=u'/v'=u'v-v'u/v²

u=2x-1  u'=2

v=x+1   v'=1

 

d'(x)= 2(x+1)-(2x-1)/(x+1)²

      = 2x+2-2x+1/(x+1)²

      = 3/(x+1)²