Câu hỏi 25
Cho $f(x) = \frac{9^{x}}{9^{x} + 3}$. Đánh giá tổng
$$
f\left(\frac{1}{1996}\right) + f\left(\frac{2}{1996}\right) + f\left(\frac{3}{1996}\right) + \cdots + f\left(\frac{1995}{1996}\right)
$$
$$
f\left(\frac{1}{1996}\right) + f\left(\frac{2}{1996}\right) + f\left(\frac{3}{1996}\right) + \cdots + f\left(\frac{1995}{1996}\right)
$$