Answer
$D=\{(x,y)\in\mathbb{R}^2| x^2+y^2\ne1, x<2\}$
Work Step by Step
The denominator cannot be equal to 0. Therefore, $x^2+y^2\ne1$, which means the values on the circle with center at the origin and radius 1.
Moreover, the value inside the logarithm must be greater than 0. Therefore, $2>x$.
Thus, $D=\{(x,y)\in\mathbb{R}^2| x^2+y^2\ne1, x<2\}$
