1.Tính
\(A=\frac{\left(1+17\right)\left(1+\frac{17}{2}\right)\left(1+\frac{17}{3}\right)+...+\left(1+\frac{17}{19}\right)}{\left(1+19\right)\left(1+\frac{19}{2}\right)\left(1+\frac{19}{3}\right)+...+\left(1+\frac{19}{17}\right)}\)
Thánh nào giúp mk với