2x^2≤3x
2x²-3x≤0
x(2x-3)≤0
0≤x≤3/2
f(x)=x^2-x+1
=x²-x+¼+¾
=(x-½﹚²+¾
当x=½时,f(x)最小值=¾
当x=3/2时,f(x)最大值=1+¾=7/4