MCQ
If $x = 2 + {2^{2/3}} + {2^{1/3}},$then ${x^3} - 6{x^2} + 6x = $
  • A
    $3$
  • $2$
  • C
    $1$
  • D
    None of these

Answer

Correct option: B.
$2$
b
(b) $x = 2 + {2^{2/3}} + {2^{1/3}}\,\,\,\, \Rightarrow x - 2 = {2^{2/3}} + {2^{1/3}}$

Cubing both sides, we get

${x^3} - 8 - 6{x^2} + 12x = 6 + 6(x - 2)$

==> ${x^3} - 6{x^2} + 6x = 2$.

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