a) Tìm x biết: \(\frac{x}{2008}-\frac{1}{10}-\frac{1}{15}-\frac{1}{21}-...-\frac{1}{120}=\frac{5}{8}\)
b) Tìm a,b \(\varepsilon\) Z biết : \(\frac{a}{9}-\frac{3}{b}=\frac{1}{18}\)
c) Cho A =\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}\)
B =\(\frac{1}{1^2}+\frac{1}{2^2}+\frac{1}{3^2}+..+\frac{1}{99^2}\)