设F(x)=(1+2/(2^x -1))×f(x)(x≠0)是偶函数,且f(x)不恒等于0,试判断f(x)是奇函数还是偶函数
问题描述:
设F(x)=(1+2/(2^x -1))×f(x)(x≠0)是偶函数,且f(x)不恒等于0,试判断f(x)是奇函数还是偶函数
答
F(x)=f(x)(2^x+1)/(2^x-1)F(-x)=f(-x)(2^(-x)+1)/(2^(-x)-1)=f(-x)(2^x+1)/(1-2^x)=-f(-x)(2^x+1)/(1-2^x)因为F(x)=F(-x)f(x)(2^x+1)/(2^x-1)=-f(-x)(2^x+1)/(1-2^x)f(x)=-f(-x)f(x)是奇函数