comment on calcule( 2 racine carrée 5 -3)(3racine5+2)

bonjour,

(2√5-3)(3√5+2) =
2√5*3√5 + 2√5*2  -3*3√5 -3*2 =
2*3*5 + 4√5 - 9√5 -6 =
30-5√5-6 =
-5√5+24