a)
(4√2 + 3√5 - 7√2)(√72 - 5√20 - 2√2)=
(4√2 + 3√5 - 7√2)(6√2 - 10√5 - 2√2)=
(48 - 40√10 - 16 + 3√10 - 30·5 - 6√10 - 84 + 70√10 + 28=
48 + 28√10 - 16 - 150 - 84 + 28=
= 28√10 - 174
b) 3√12=6√3
√45=3√5
6√3/(3√5-4√2)+5√(2×4×18)=
=6√3/(3√5-4√2) +5√144
=6√3/(3√5-4√2) +5×12
=6√3/(3√5-4√2) +60
=[6√3+60(3√5-4√3)]/(3√5-4√2)
=(6√3+180√5-240√3)/(3√5-4√2)
=(180√5-234√3)/(3√5-4√2)
