a)√3(√12-2√27)=√3(2√3-2·3√3)=√3(2√3-6√3)=√3·(-4√3)=-4·3=-12
b)√48-2√3(2-5√12)=4√3-2√3(2-5·2√3)=4√3-2√3(2-10√3)=4√3-4√√3+20·3=60
c)(3+√3)(2+√3)=6+3√3+3√3+3=9+6√3
d)(√6+√5)²-√210=6+2√5+5-√210=11+2√5-√210