(a+b)²+|b-三分之一|=0∴a+b=0b-1/3=0∴a=-1/3b=1/3(5a²b-ab²-3ab)-(2ab+5a²b-2ab²)=5a²b-ab²-3ab-2ab-5a²b+2ab²=ab²-5ab=ab(b-5)=-1/9(1/3-5)=14/27