The given problem defines a region $R = [1, 4] \times [2, 3]$ and a function $f(x, y) = \ln(x + y)$.

Problem Interpretation

The region $R$ refers to a rectangle in the $xy$-plane, with $x$ ranging from 1 to 4, and $y$ ranging from 2 to 3. The function $f(x, y) = \ln(x + y)$ is a natural logarithm function applied to the sum of $x$ and $y$.

Is there something specific you want to do with this information? For example, would you like to evaluate the function over this region, find the integral of $f(x, y)$ over $R$, or analyze some other property of the function within this region?

Let me know how you'd like to proceed!