抛物线y=f(x)=2x²-ax+1开口向上,对称轴为直线x=a/4.
a/4∈[0,1]时,g(a)=f(a/4)=1-a^2/8;
a/41时,g(a)=f(1)=3-a.
a/41/2时h(a)=f(0)=1.
综上,g(a)={1,a