#### Answer

(a) Hyperbola
(b) Parabola
(c) Ellipse
(d) No conic section.

#### Work Step by Step

(a) The equation can be written in the form
$\frac{x^2}{12/4}-\frac{y^2}{12/9}=1$
Thus, it is a hyperbola.
(b) The equation can be written in the form
$y^2=(4/9)x$
Thus, it is a parabola.
(c) The equation can be written in the form
$\frac{x^2}{12/4}+\frac{y^2}{12/9}=1$
Thus, it is an ellipse.
(d) This equation can not be formed to look like one of the conic section formulas in this chapter. Thus, it does not correspond to any conic section.