Tìm x thỏa mãn
a, \(\frac{1}{1.4}+\frac{1}{4.7}+...+\frac{1}{97.100}=|\frac{x}{3}|\)
b, \(\frac{4}{1.5}+\frac{4}{5.9}+...+\frac{4}{97.101}=|\frac{5x-4}{101}|\)
c,\(\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right)...\left(1-\frac{1}{100}\right)=|x-1\frac{99}{100}|\)