Tính
giúp vs ạ
----- Nội dung ảnh -----
Bài 8. Tính \( A = 1 - \left( \frac{3}{4} \right)^2 - \left( \frac{3}{4} \right)^3 + \left( \frac{3}{4} \right)^4 - \left( \frac{3}{4} \right)^5 - \ldots - \left( \frac{3}{4} \right)^{2019} + \left( \frac{3}{4} \right)^{2020} \)
----- Nội dung ảnh -----
Bài 8. Tính \( A = 1 - \left( \frac{3}{4} \right)^2 - \left( \frac{3}{4} \right)^3 + \left( \frac{3}{4} \right)^4 - \left( \frac{3}{4} \right)^5 - \ldots - \left( \frac{3}{4} \right)^{2019} + \left( \frac{3}{4} \right)^{2020} \)