已知x^2+2y^2=1.求2x+5y^2的最小值_数学解答

已知x^2+2y^2=1.求2x+5y^2的最小值

人气：133 ℃　时间：2020-05-08 19:52:09

解答

x^2+2y^2=1
|x|<=1
y^2=(1-x^2)/2
2x+5y^2
＝2x+(1－x^2)(5/2)
=-(5/2)x^2+2x+(5/2)=f(x)
|x|<=1
f(-1)=min=-2