Второе по действиям:
1) 351^3-351^2=351^2(351-1)=351^2*350
2) -350^3-350^2=-351^2(350+1)=-350^2*351
3) 351^2*350-351*350-350^2*351=351*350(351-1-350)=0
Первое:
27sqrt(5/3)-6sqrt(15)-15sqrt(5/3)+18sqrt(25/9)=27sqrt(5/3)-6sqrt(15)-15sqrt(5/3)+30=
=3(9sqrt(5/3)-2sqrt(15)+5sqrt(5/3)+10)=3(9sqrt(5/3)-2sqrt(15)-sqrt(15)+10)=
=3(9sqrt(5/3)-3sqrt(15)+10)=3(3(3sqrt(5/3)-sqrt(15))+10)=3(3(sqrt(15)-sqrt(15))+10)=30