Réponses

2014-05-13T21:46:18+02:00
1- A=(9x-2)(3x+5) +81 x2-4
  A = 9x X 3x + 9x X 5 - 2 X 3x -2 X 5 + 81 X 2-4
  A = 27x² + 45x - 6x - 10 + 81 X 2-4
  A = 27x² + 39x - 10 + 162 -4 
  A = 27x² + 39x +148 

3- 27 X (-2/5) + 39X (-2/5) + 148
   = -10.8 - 15.6 + 148
   = 121.6

4 - 27x² + 39x + 148 = 0
     27x² + 39x  = -148
    (27 X x) + (27 X x) + 39x = -148
    27 x + 27x + 39x = -148
    93x = -148
     x = -148/93 
     x = 1.59