Question

用配方法求2x的平方-7x+2的最小值

Answer 1

根据题意列式计算如下：
2x²-7x+2
=2(x²-7x/2)+2
=2(x-7/4)²-(7/4)²+2
=2(x-7/4)²+2-49/16
=2(x-7/4）²-17/16
所以，最小值是-16分之17

Answer 2

f(x)

=2x^2 -7x+2
=2[x^2 -(7/2)x ] +2
=2[x^2 -(7/2)x +(7/4)^2 ] +2 - 49/8
=2(x-7/4)^2 - 33/8
min f(x) = - 33/8