Let \( f : R \to R \) be a function given bywhere \( \alpha, \beta \in R \). If \( f \) is continuous at \( x = 0 \), then \( \alpha^2 + \beta^2 \) is equal to:
\( 3 \)
\( 12 \)
\( 6 \)
\( 48 \)