Answer
ellipse, center $(2,1)$, vertices $(-1,1),(5,1)$, foci $(2-\sqrt 5,1),(2+\sqrt 5,1)$
Work Step by Step
1. Given $4x^2+9y^2-16x-18y=11$ or $\frac{(x-2)^2}{9}+\frac{(y-1)^2}{4}=1$, we can identify it as an ellipse with a horizontal major axis, $a=3, b=2$ and $c=\sqrt {a^2-b^2}=\sqrt 5$.
2. We can find its center $(2,1)$, vertices $(-1,1),(5,1)$, foci $(2-\sqrt 5,1),(2+\sqrt 5,1)$
