A
1)7(√(3a)-√(5b)/[6(√(3a)+√(5b) * 3(√(3a+√5b))²/[(√(3a)-√(5b))(√(3a)+√(5b))]=
=7/2=3,5
b
1)(√a+3√b)(a-3√(ab)+9b)/[3(√a+3√b)] -√(ab)=(a-3√(ab)+9b)/3 -√(ab)=
=(a-3√(ab)+9b-3√(ab))/3=(√a-3√b)²/3
2)(√a-3√b)²/3 * 9(√a+3√b)²/[(√a-3√b)(√a+3√b)]=3(√a-3√b)(√a+3√b)=
=3(a-9b)=3a-27b