Réponses

2014-02-11T14:29:32+01:00
(2a+3)^{2} =5 <=>  (2a+3)^{2}-5=0
<=>  (2a+3)^{2} -  \sqrt{5} ^{2} =0
<=> (2a+3- \sqrt{5})(2a+3+ \sqrt{5}  )=0
<=> 2a=-3+ \sqrt{5} ou 2a=-3- \sqrt{5}
<=> a= \frac{-3+ \sqrt{5} }{2} ou a= \frac{-3- \sqrt{5} }{2}