Bài 9A.  Let M = $\frac{3}{1.2}$ -$\frac{5}{2.3}$ +$\frac{7}{3.4}$-...- $\frac{201}{y}$  Bài 9B. In the "magic" square beside, sum of numbers in all rows, columns and diagonals are the same. Find z.

Bài 94. Let M Bài 9B. 3 5 7 1.2 2.3 3.4 1 1 Bài 9C. Cho S = ++ 5² 6 ² 7 ² 201 100.101 In the "magic" square beside, sum of numbers in all rows, columns and diagonals are the same. Find z. +...+ . Prove that the value of M is not a natural number. 1 1 + Chứng minh: Se 99² 100 s<1/1/1 4 ...