Câu 3:
a, Chứng minh rằng nếu:
(\(\overline{ab}\)+\(\overline{cd}\)+\(\overline{eg}\)) ⋮ 11 thì \(\overline{abcdeg}\) ⋮ 11
b, Cho E = 92-\(\dfrac{1}{9}-\dfrac{2}{10}-\dfrac{3}{11}-...-\dfrac{92}{100}\); F= \(\dfrac{1}{45}+\dfrac{1}{50}+\dfrac{1}{55}+...+\dfrac{1}{500}\)Tính \(\dfrac{E}{F}\)