Question

设f(x)=1/x+1,则f(f(x))=?

详细过程..谢谢

Answer 1

把f(x)当成x代入表达式中，得f(f(x))=1/f(x)+1,结果是(1+2x)/+(1+x)

Answer 2

f(f(x))=f(1/x+1)=1/(1/x+1)+1
=1/(1+x/x)+1
=x/(x+1)+1
=(2x+1)/(x+1)

Answer 3

f(f(x))=1/（1/x +1）+1=x/（x+1） +1