Question

如何求证,y=lg(x+根号1+x的二次方）是奇函数,

Answer 1

y=f(x)=lg(x+√ (x^2+1))
f(-x)=lg[-x+√ (x^2+1)]
=lg[√ (x^2+1))-x]
=lg{1/[√ (x^2+1))+x]}
=lg[√ (x^2+1))+x]^(-1)
=-lg[√ (x^2+1))+x]
=-lg[x+√ (x^2+1)]
=-f(x)
∴函数y=lg(x+√ (x^2+1))为奇函数.