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Question Number 63909 by gunawan last updated on 11/Jul/19
The integral part of (8 + 3(√7) )^(20)  is even.
$$\mathrm{The}\:\mathrm{integral}\:\mathrm{part}\:\mathrm{of}\:\left(\mathrm{8}\:+\:\mathrm{3}\sqrt{\mathrm{7}}\:\right)^{\mathrm{20}} \:\mathrm{is}\:\mathrm{even}. \\ $$
Commented by gunawan last updated on 11/Jul/19
true or false
$$\mathrm{true}\:\mathrm{or}\:\mathrm{false} \\ $$$$ \\ $$
Answered by Hope last updated on 11/Jul/19
  (8+3(√7) )^(20)   8^(20) +20c_1 8^(19) (3(√7) )+20c_2 (8^(18) )(3(√7) )^2 +...+(3(√7) )^(20)   last term is integral part →3^(20) ×7^(10)  but it is odd  so sum of all integral part is odd  given statement is false
$$ \\ $$$$\left(\mathrm{8}+\mathrm{3}\sqrt{\mathrm{7}}\:\right)^{\mathrm{20}} \\ $$$$\mathrm{8}^{\mathrm{20}} +\mathrm{20}{c}_{\mathrm{1}} \mathrm{8}^{\mathrm{19}} \left(\mathrm{3}\sqrt{\mathrm{7}}\:\right)+\mathrm{20}{c}_{\mathrm{2}} \left(\mathrm{8}^{\mathrm{18}} \right)\left(\mathrm{3}\sqrt{\mathrm{7}}\:\right)^{\mathrm{2}} +…+\left(\mathrm{3}\sqrt{\mathrm{7}}\:\right)^{\mathrm{20}} \\ $$$${last}\:{term}\:{is}\:{integral}\:{part}\:\rightarrow\mathrm{3}^{\mathrm{20}} ×\mathrm{7}^{\mathrm{10}} \:{but}\:{it}\:{is}\:{odd} \\ $$$${so}\:{sum}\:{of}\:{all}\:{integral}\:{part}\:{is}\:{odd} \\ $$$${given}\:{statement}\:{is}\:{false} \\ $$

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