A = \( \left( \frac{1}{3} + \frac{3}{x^2 - 3x} \right) : \left( \frac{x^2}{27 - 3x^2} + \frac{1}{x + 3} \right) \)

----- Nội dung ảnh -----
A = \( \left( \frac{1}{3} + \frac{3}{x^2 - 3x} \right) : \left( \frac{x^2}{27 - 3x^2} + \frac{1}{x + 3} \right) \)

a) Tìm TXĐ, HG A
b) Tìm x để A < 1