23.已知函数f(x)=ax2+bx+a(a>0)f(x)=ax^{2}+bx+a(a>0)f(x)=ax2+bx+a(a>0),fff(1)=1=1=1,则f(1a)f(\frac{1}{a})f(a1)的最小值为 ___22−22\sqrt{2}-222−2___.