A= \(\frac{-1}{2}.\frac{-2}{3}.\frac{-3}{4}.\frac{-4}{5}.....\frac{-1011}{1012}\)
A=\(-\frac{1.2.3.4.5.....1011}{1.2.3.4.5.....1011.1012}\)=\(\frac{-1}{1012}\)
B= 162.\(\frac{1}{5}\)+\(\frac{4}{5}\).\(\frac{81}{79}\)
B= \(\frac{162}{5}\)+\(\frac{324}{395}\)tự tính tiếp nhé