当-(2a+1)/2≤1即a≥-3/2时 f(x)max=f(2)=a�0�5+7a+6=0故a=-6(舍去),a=-1当-(2a+1)/2＞1，即：a＜-3/2时，f(x)max=f(0)=a�0�5+3a=0．故a=0（舍去）或a=-3．综上得：a的取值为：a=-1或a=-3．
