Bonjour
Il faut utilier la propriété qui dit ,a,×,b,,=,,a,,×,,b,\sqrt{,a,\times ,b,},=,\sqrt{,a,},\times ,\sqrt{,b,},a,×,b,
,=,,a,
,×,,b,
18,=,,9,×,2,,=,,9,,×,,2,\sqrt{18},=,\sqrt{,9, \times , 2,},=, \sqrt{,9,},\times ,\sqrt{,2,}18
,=,,9,×,2,
,=,,9,
,×,,2,
Tu essayes