Réponses

2014-02-16T11:29:35+01:00


a²-b²=(a+b)(a-b)     a²=4x²     a=2x     b²=(x-5)²   b=x-5

((2x+(x-5))((2x-(x-5))=(2x+x-5)(2x-x+5)=(3x-5)(x+5)