3a^2b(1/3ab+b^2)+(a^2b-ab^2)×（-5ab)
=a+3a^2b^2-5a^3b^3+5a^2b^3然后 答案呢亲3a^2b(1/3ab+b^2)+(a^2b-ab^2)×（-5ab)
=a+3a^2b^3-5a^3b^2+5a^2b^3
=a+8a^2b^3-5a^3b^2
=a(1+8ab^3-5a^2b^2)