bonsoir,

C = 5-3V2

D = 3+2V2

C+D = (5-3V2)+(3+2V2)= enleve les () et reduis

C-D = (5-3v)-(3+2V2) = .......................

C*D = (5-3V2)(3+2V2)=
      (5*3 +5*2V2 -3V2*3 +-3V2*2V2) =
       15+10V2-9V2-6 =
       9+V2