a>0,b>0,a+b=1,求证:(√ a+1/2)+√(b+1/2)<=2

来源:百度知道 编辑:UC知道 时间:2024/06/22 08:52:50
“( √ )”为根号下

均值不等式(X+Y)/2<=√(X^2+Y^2)
(证明用两边平方)
记X=(√ a+1/2),Y=√(b+1/2)即可

均值不等式(X+Y)/2<=√(X^2+Y^2)
(x^2+y^2)/(x-y)

=[(x-y)^2+2xy]/(x-y)

=(x-y)+2xy/(x-y)

=(x-y)+2/(x-y)

>=2√(x-y)*2/(x-y)=2√2

当:x-y=2/(x-y)时取最小值。是2√2

即:x^2-2xy+y^2=2

x^2+y^2=4

x+y=√6
x-y=√2

X=(√6+√2)/2,Y=(√6-√2)/2