Answer
$${\text{ ellipse}}$$
Work Step by Step
$$\eqalign{
& \frac{{{x^2}}}{4} = 1 - \frac{{{y^2}}}{9} \cr
& {\text{Add }}\frac{{{y^2}}}{9}{\text{ to both sides}} \cr
& \frac{{{x^2}}}{4} + \frac{{{y^2}}}{9} = 1 \cr
& or \cr
& \frac{{{x^2}}}{{{{\left( 2 \right)}^2}}} + \frac{{{y^2}}}{{{{\left( 3 \right)}^2}}} = 1 \cr
& {\text{The equation is written in the form }}\frac{{{x^2}}}{{{b^2}}} + \frac{{{y^2}}}{{{a^2}}} = 1\,\,\,\,\left( {{\text{Where }}a > b} \right) \cr
& {\text{Therefore,}} \cr
& {\text{The graph of the equation }}\frac{{{x^2}}}{4} = 1 - \frac{{{y^2}}}{9}{\text{ is an ellipse}} \cr} $$
