2x²-6x+1=2(x²-3x)+1
=2(x-3/2)²-7/2
所以当x=3/2时有最小值,最小值为-7/2详细点2x²-6x+1=2(x²-3x)+1 =2[x²-2×3/2*x+(3/2)²-(3/2)²]+1 =2[(x-3/2)²-9/4]+1=2(x-3/2)²-9/2+1=2(x-3/2)²-7/2这是一个开口向上的二次函数，顶点为(3/2，-7/2)所以有最小值-7/2