2 réponses
On a :
21,363636...=21+0.363636...
On prend 0.363636... on a :
100*0.363636...=36.363636...=36+0.363636...
On a donc 100*0.36363636...=36+0.363636 soit 100*0.363636...-0.363636...=36
soit 99*0.363636...=36 soit 0.363636...=36/99
On a donc 21.363636...=21+0.363636...=21+36/99=21+(4*9)/(11*9)=21+4/11=235/11
Voilà 21.363636...=235/11
21,363636...=21+0.363636...
On prend 0.363636... on a :
100*0.363636...=36.363636...=36+0.363636...
On a donc 100*0.36363636...=36+0.363636 soit 100*0.363636...-0.363636...=36
soit 99*0.363636...=36 soit 0.363636...=36/99
On a donc 21.363636...=21+0.363636...=21+36/99=21+(4*9)/(11*9)=21+4/11=235/11
Voilà 21.363636...=235/11