bonjour,
1.1) (1+√5)² = 1+2√5+5 = 2√5+6
1.2) (2√5+6)/4 = (√5+3)/2
1.3) (1+√5)/2 +1 =
(1+√5+2)/2 = (√5+3)/2
1.4) voir réponse 1.2 et 1.3
2.1) 1/(1+√5)/2 =
1*2/1+√5 =
2/(1+√5) =
2(1-√5)/(1+√5)(1-√5)=
2-2√5/-4 = (-1+√5)/2
2.2) (1+√5)/2 -1 =
(1+√5-2)/2 =
(√5-1)/2
2.3) voir réponses 2.1 et 2.2