Let \( P_n=\alpha^n+\beta^n,\, n\in \mathbb{N} \). If \( P_{10}=123,\, P_9=76,\, P_8=47 \) and \( P_1=1 \), then the quadratic equation having roots \( \frac{1}{\alpha} \) and \( \frac{1}{\beta} \) is:
\( x^2 + x + 1 = 0 \)
\( x^2 - x - 1 = 0 \)
\( x^2 - x + 1 = 0 \)
\( x^2 + x - 1 = 0 \)