1) A = \( \frac{5}{\sqrt{1}} + \frac{1}{1-a} + \frac{2}{a^2} \): \( \frac{2n+1}{1-a^3} \) a) Tìm: ĐK A b) Tìm \( x \in \mathbb{Z} \) sao cho \( A \in \mathbb{Z} \) c) Tìm \( x \) để \( |A| = A \)