Question 194 of 347MediumMCQ
The lowest integer which is greater than (1+101001)10100 is
Solutions · 1
Official solution
Let \[P = {\left( {1 + {1 \over {{{10}^{100}}}}} \right)^{{{10}^{100}}}}\]
Let x=10100
\[ \Rightarrow P = {\left( {1 + {1 \over x}} \right)^x}\]
\[ \Rightarrow P = 1 + (x)\left( {{1 \over x}} \right) + {{(x)(x - 1)} \over {\left| \!{\underline {\,
2 \,}} \right. }}.{1 \over {{x^2}}} + {{(x)(x - 1)(x - 2)} \over {\left| \!{\underline {\,
3 \,}} \right. }}.{1 \over {{x^3}}} + ....\]
(upto 10100 + 1 terms)
\[ \Rightarrow P = 1 + 1 + \left( {{1 \over {\left| \!{\underline {\,
2 \,}} \right. }} - {1 \over {\left| \!{\underline {\,
2 \,}} \right. {x^2}}}} \right) + \left( {{1 \over {\left| \!{\underline {\,
3 \,}} \right. }} - ...} \right) + ...\] so on
\[ \Rightarrow P = 2 + \left( {Positive\,value\,less\,than\,{1 \over {\left| \!{\underline {\,
2 \,}} \right. }} + {1 \over {\left| \!{\underline {\,
3 \,}} \right. }} + {1 \over {\left| \!{\underline {\,
4 \,}} \right. }} + ...} \right)\]
Also \[e = 1 + {1 \over {\left| \!{\underline {\,
1 \,}} \right. }} + {1 \over {\left| \!{\underline {\,
2 \,}} \right. }} + {1 \over {\left| \!{\underline {\,
3 \,}} \right. }} + {1 \over {\left| \!{\underline {\,
4 \,}} \right. }} + ...\]
\[ \Rightarrow {1 \over {\left| \!{\underline {\,
2 \,}} \right. }} + {1 \over {\left| \!{\underline {\,
3 \,}} \right. }} + {1 \over {\left| \!{\underline {\,
4 \,}} \right. }} + ... = e - 2\]
\[\Rightarrow\] P = 2 + (positive value less than e - 2)
\[\Rightarrow\] P \[\in\] (2, 3)
\[\Rightarrow\] least integer value of P is 3
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