(7√3+√48-√75)*√3=(7√3+4√3-5√3)√3=6√3*√3=18
(6-√5)(2+7√5)=12-2√5+42√5-35=40√2-23
(5√2+6√3)(6√2-5√3)=5*6*2+36√6-25√6-90=11√6-30
(√17-√11)(√17+√11)=17-11=6
(2√x-5√y)(2√x+5√y)=2*2*х-5*5*у=4х-25у
(√6-2)^2=6-4√6+4=10-4√6
(3√7-2√3)^2=3*3*7-2*3√21-2*3*√21-2*2*3=
=75-12√21