1.
Let f(x)={loge(1+5x)loge(1+ax)x,x010,x=0f(x) = \begin{cases} \frac{\log_e(1+5x) - \log_e(1+ax)}{x}, & x \neq 0 \\ 10, & x = 0 \end{cases} be continuous at x=0x = 0. Then aa is equal to: