preuve-a-HH-1-H-b-HH-H-c-H-1-H-

Question Number 163885 by SANOGO last updated on 11/Jan/22

$${preuve} \\ $$$$\left.{a}\right){HH}^{−\mathrm{1}} ={H} \\ $$$$\left.{b}\right){HH}={H} \\ $$$$\left.{c}\right){H}^{−\mathrm{1}} ={H} \\ $$