Answer
$(2\sqrt2, 0)$
Work Step by Step
Simplify the radical coordinate of the first point to obtain:
$(\sqrt{18}, -4) = (\sqrt{9(2)}, -4)=(3\sqrt2, -4)$
RECALL:
The midpoint of $(x_1, y_1)$ and $(x_2, y_2)$ can be found using the midpoint formula
$\text{midpoint}=\left(\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2}\right)$
Use the formula above to obtain:
$\text{midpoint}
\\=\left(\dfrac{3\sqrt2+\sqrt2}{2}, \dfrac{-4+4}{2}\right)
\\=\left(\dfrac{4\sqrt2}{2}, \dfrac{0}{2}\right)
\\=(2\sqrt2, 0)$
