f(x)=lg(1+x)/(1-x) (-1

分类: 作业答案 • 2022-01-09 18:04:51

问题描述：

答

f((3x+x^3)/(1+3x^2))=lg {[(1+3x+3x^2+x^3)/(1+3x^2)]/[(1-3x+3x^2-x^3)/(1+3x^2)]}
=lg[(1+x)^3/(1-x)^3]
=3lg[(1+x)/(1-x)]
=3f(x)