A = 1/30 + 1/42 + 1/56 + 1/72 + 1/90
A = 1/5x6 + 1/6x7 + 1/7x8 + 1/8x9 + 1/9x10
A = 1/5 - 1/6+ 1/6 -1/7 + 1/7 - 1/8 + 1/8 - 1/9 + 1/9 - 1/10
A = 1/5 - 1/10
A = 1/10
\(A=\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}\)
\(\Rightarrow A=\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}\)
\(\Rightarrow A=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}\)
\(\Rightarrow A=\frac{1}{5}-\frac{1}{10}\)
\(\Rightarrow A=\frac{2-1}{10}\)
\(\Rightarrow A=\frac{1}{10}\)
A = \(\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}\)
A =\(\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}\)
A = \(\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}\)
A = \(\frac{1}{5}-\frac{1}{10}\)
A =\(\frac{1}{10}\)