Câu hỏi 96
Tính giá trị của
$$
\frac{7}{12} + \frac{5}{12} \times \frac{7}{11} + \frac{5}{12} \times \frac{4}{11} \times \frac{7}{10} + \frac{5}{12} \times \frac{4}{11} \times \frac{3}{10} \times \frac{7}{9}
$$
$$
\frac{7}{12} + \frac{5}{12} \times \frac{7}{11} + \frac{5}{12} \times \frac{4}{11} \times \frac{7}{10} + \frac{5}{12} \times \frac{4}{11} \times \frac{3}{10} \times \frac{7}{9}
$$