137- For which value of $a$, the distance between the foci of the hyperbola $3x^2 + 4y^2 + 16y + a = 0$ equals $2$? (1) $2$ (2) $4$ (3) $6$ (4) $8$
\textbf{137-} For which value of $a$, the distance between the foci of the hyperbola $3x^2 + 4y^2 + 16y + a = 0$ equals $2$?
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(1) $2$ \hfill (2) $4$ \hfill (3) $6$ \hfill (4) $8$
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