Tính nhanh:
giúp mình bài 8, 9 này với ạ !!
----- Nội dung ảnh -----
8. Tính nhanh:
a) \( A = \frac{1}{3} + \frac{3}{5} + \frac{5}{7} + \frac{9}{11} + \frac{11}{13} + \frac{13}{15} + \frac{9}{11} + \frac{7}{5} + \frac{3}{1} \);
b) \( B = \frac{1}{9.10} + \frac{1}{8.9} + \frac{7.8}{2.3} + \frac{1}{1.2} \).
9. Tính nhanh:
a) \( A = \frac{50}{13} + \frac{4}{15} + \frac{2}{17} \);
\( = \frac{8}{4} + \frac{4}{100} - \frac{13}{15} - \frac{17}{4} \);
b) \( B = \frac{1}{8} + \frac{1}{24} + \frac{1}{48} + \frac{1}{80} + \frac{1}{120} \);
c) \( C = \frac{1}{19} + \frac{9}{19.29} + \ldots + \frac{9}{1999.2009} \).
----- Nội dung ảnh -----
8. Tính nhanh:
a) \( A = \frac{1}{3} + \frac{3}{5} + \frac{5}{7} + \frac{9}{11} + \frac{11}{13} + \frac{13}{15} + \frac{9}{11} + \frac{7}{5} + \frac{3}{1} \);
b) \( B = \frac{1}{9.10} + \frac{1}{8.9} + \frac{7.8}{2.3} + \frac{1}{1.2} \).
9. Tính nhanh:
a) \( A = \frac{50}{13} + \frac{4}{15} + \frac{2}{17} \);
\( = \frac{8}{4} + \frac{4}{100} - \frac{13}{15} - \frac{17}{4} \);
b) \( B = \frac{1}{8} + \frac{1}{24} + \frac{1}{48} + \frac{1}{80} + \frac{1}{120} \);
c) \( C = \frac{1}{19} + \frac{9}{19.29} + \ldots + \frac{9}{1999.2009} \).