[tex]GEOMETRIC \: \: PROGRESSIONS \\ \\ \\
Taking \: \: L.H.S. \: \\ \\ 0.999... \: = \: 0 \: + \: \frac{9}{10} \: + \: \frac{9}{100} \: + \: \frac{9}{1000} + \: ... \: \: \infty \\ \\ \\ 0.999... \: = \: \frac{9}{10} \: ( \: 1 \: + \frac{1}{10} \: + \: \frac{1}{100} \: + \: \frac{1}{1000} + \: ... \: \: \infty \: \: ) \\ \\ \\ 0.999... \: = \: \frac{9}{10} \: ( \: 1 + \: \: \frac{1}{ {10}^{1} } \: + \: \frac{1}{ {10}^{2} } \:+ \: \frac{1}{ {10}^{3} } \: + \: ... \: \: \infty \: ) \\ \\ \\ As \: we \: can \: see \: \: , \: \\ \\ Above \: expression \: in \: bracket \: forms \: a \: \\ Infinite \: Geometric \: Progression \\ \\ Where \: \: ,\: \: \: \: \\ a = 1 \: \: \: \: \: and \: \: \: \: \: r = \frac{1}{10} \\ \\ Sum \: of \: Infinite \: Geometric \: \\ Progression \: \: = \: \: \frac{a}{1 - r} \\ \\ \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{1}{1 - \frac{1}{10} } \: \: = \: \: \frac{1}{ \frac{9}{10} } \: \: = \: \: \frac{10}{9} \\ \\ \\ Putting \: in \: above \: , \: we \: get \: - \: \\ \\ 0.999... \: \: = \: \: \frac{9}{10} \times \frac{10}{9} \: \: \\ \\ \\ 0.999... \: \: = \: \: 1 \: \: = \: R.H.S. \\ \\ Hence , \: above \: expression \: is \: TRUE \: \: :)[/tex]
