Réponses

2014-01-18T22:08:15+01:00
(x-1)(x+1)=0
2 solutions x= 1 ou x=-1

x^2-3x=18\\x^2-3x-18=0\\(x- \frac{3}{2})^2 -  \frac{9}{4} - 18=0\\(x- \frac{3}{2})^2 -  \frac{9}{4} -  \frac{72}{4}=0\\(x- \frac{3}{2})^2 -  \frac{81}{4}=0\\(x- \frac{3}{2})^2 -  (\frac{9}{2})^2=0\\(x- \frac{3}{2} - \frac{9}{2})(x- \frac{3}{2} + \frac{9}{2})=0\\(x- 6)(x+3)=0\\

2 solutions x=6 ou x=-3

En espérant t'avoir aidé.