(1)f(-1)=-f(a)-1-2a+a^2=-(-a^2+2a^2+a^2)求根a=1 a=-1/3（舍）即：f(x)=-x^2+2x+1(2)f(x)=-(x-1)^2+2当x=1时f(x)最大，f(x)最大值为2
