a/
\(=\dfrac{1x16}{2x16}+\dfrac{1x8}{4x8}+\dfrac{1x4}{8x4}+\dfrac{1x2}{16x2}+\dfrac{1}{32}\)
\(=\dfrac{16+8+4+2+1}{32}=\dfrac{31}{32}\)
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b/ msc : 243
\(=\dfrac{1x81}{3x81}+\dfrac{1x27}{9x27}+\dfrac{1x9}{27x9}+\dfrac{1x3}{81x3}+\dfrac{1}{243}\)
\(=\dfrac{81}{243}+\dfrac{27}{243}+\dfrac{9}{243}+\dfrac{3}{243}+\dfrac{1}{243}\)
\(=\dfrac{81+27+9+3+1}{243}=\dfrac{121}{243}\)
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