Réponses

2014-04-25T19:25:34+02:00
A²=14+6√5
B²=14-6√5
AB=-4
(A+B)²=20
A/B + B/A = A²/BA + B²/AB = (14+6√5)/(-4) + (14-6√5)/(-4) = 14+6√5+14-6√5/(-4) = 28/(-4) = (-7)
2014-04-25T19:35:52+02:00


A=V5+3    A²=(V5+3)²=5+6V5+9=14+6V5

B=V5-3    B²=(V5-3)²= 5-6V5+9=14-6V5

AB= (V5+3)(V5-3)=5-9=-4

(A+B)²=[(V5+3)+(V5-3)]²=(V5+3+V5-3)²=2V5²=2V5 x 2V5=20

A/B+B/A= (A²+B²)/AB=(14+6V5+14-6V5)/-4=28/-4=-7