If ${(1 - x + {x^2})^n} = {a_0} + {a_1}x + {a_2}{x^2} + .... + {a_{2n}}{x^{2n}}$, then ${a_0} + {a_2} + {a_4} + .... + {a_{2n}} = $
If ${(1 - x + {x^2})^n} = {a_0} + {a_1}x + {a_2}{x^2} + .... + {a_{2n}}{x^{2n}}$, then ${a_0} + {a_2} + {a_4} + .... + {a_{2n}} = $
- A
$\frac{{{3^n} + 1}}{2}$
- B
$\frac{{{3^n} - 1}}{2}$
- C
$\frac{{1 - {3^n}}}{2}$
- D
${3^n} + \frac{1}{2}$
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