Réponses

2012-10-11T16:20:55+02:00

4x²=25

4x²-25=0

(2x)²-5²=0 on applique a²-b²=(a-b)(a+b)2x-1

(2x+5)(2x-5)=0

2x+5=0 et 2x-5=0

x=-5/2 et x=5/2

S={-5/2;5/2}

 

(2x-1)²=3

(2x-1)²-3=0

(2x-1)^{2}-(\sqrt{3})^{2}=0

(2x-1-\sqrt{3})(2x-1+\sqrt{3})=0

2x-1-\sqrt{3}=0 et2x-1+\sqrt{3}=0

x=(1+\sqrt{3})/2etx=(1-\sqrt{3})/2