f'(x)=-2x+a.令f'(x)=0.则x=a/21)当a/2≤-1即a≤-2时,f(x)在[-1,1]上单调递减.此时f(x)max=f(-1)=-1/2-5/4a=2,求得a=-2 符合题意2)当a/2≥1即a≥ 2时,f(x)在[-1,1]上单调递增.此时f(x)max=f( 1)=-1/2+3/4a=2,求得a=1...