Tìm x
2x-3=x+\(\frac{1}{2}\)
4x-(2x+1)=3-\(\frac{1}{3}\) +x
Tính
a \(\frac{1}{1\cdot4}\) +\(\frac{1}{4\cdot7}\) +\(\frac{1}{7\cdot10}\) +....+\(\frac{1}{100\cdot103}\)
b \(\frac{8}{9}\) -\(\frac{1}{72}\) -\(\frac{1}{56}\) -\(\frac{1}{42}\) -....-\(\frac{1}{6}\) -\(\frac{1}{2}\)