question_answer

If \[{{e}^{f(x)}}=\frac{10+x}{10-x},\] \[x\in (-10,10)\] and \[f(x)=kf\,\,\left( \frac{200x}{100+{{x}^{2}}} \right)\],  then find the value of k.

A)  0.9                              

B)  0.8

C)  0.7                              

D)  0.6

E)  None of these