解：原式=5*（3a^2-ab^2）-2(ab^2+3a^2b)=15a^2-5ab^2-2ab^2-6a^2b=15a^2-6a^2b-7ab^2带入a=-1/2，b=1/3可得：15*1/4+1+7/18=15/4+1+7/18=185/36
