y`=1/(2sqrt(12)) * (12x)`=6/sqrt(12x)
(y`)^2=36/12x=3/x
S_(поверхности Ох)=2π ∫ ^(12)_(0)sqrt(12x)*sqrt(1+(3/x))dx=
=2π ∫ ^(12)_(0)sqrt(12)*sqr(x+3)dx=
=2sqrt(12)*π ∫ ^(12)_(0)sqr(x+3)dx=
=4sqrt(3)*π *(x+3)^(3/2)/(3/2)| ^(12)_(0)=
= [b](8sqrt(3)/3)*π*( 15^(3/2)-3^(3/2))[/b]