2a+3b-9=0 a-9b-8=0解得：a=5 b=1/33(-3a)^2a(-b^3)+(-3ab^2)^3+(-3a)^2(1/5b)^2=3(9a^2)a(-b^3)+(-27a^3b^6)+(9a^2)(1/25b^2)=-27a^3b^3-27a^3b^6+9/25a^2b^2=-27×125×(1/27)-27×125×(1/729)+(9/25)×25×(1/9)...