=[(e^2x)-2+(e^-2x)]^(1/2)+[(e^(2x+2+e^(-2x)]^(1/2)
={[e^x-e^(-x)]^2}^(1/2)+{[(e^x+e^(-x)]^2}^(1/2)
e^x>=e^(-x)时
=e^x-e^(-x)+e^x+e^(-x)=2e^x
e^x
=[(e^2x)-2+(e^-2x)]^(1/2)+[(e^(2x+2+e^(-2x)]^(1/2)
={[e^x-e^(-x)]^2}^(1/2)+{[(e^x+e^(-x)]^2}^(1/2)
e^x>=e^(-x)时
=e^x-e^(-x)+e^x+e^(-x)=2e^x
e^x