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Meilleure réponse !
2013-12-10T19:58:13+01:00
A) (5*(-1)-2)²-(-1-7)*(5*(-1)-2) = (-5-2)²-(-7) (-5-2)= 49- 49 =0 .
b) (2*()+1)²-4.= (-6/2 +1)²-4 =(-3+1)²-4 = -2²-4 =4-4= 0  
c) (2x-1)(2x-1)-4*(2-x) = (2x-1)² - 4 (2-x) = 4x²-4x+1 -8 +4x = 4x² -7