1. The problem is to understand the concepts of domain and range in functions, specifically for class 12 students following the Punjab Board curriculum in Pakistan. 2. The domain of a function is the set of all possible input values (usually $x$) for which the function is defined. 3. The range of a function is the set of all possible output values (usually $y$) that the function can produce. 4. For example, if we have a function $f(x) = \sqrt{x}$, the domain is all $x \geq 0$ because square root of negative numbers is not defined in real numbers. 5. The range of $f(x) = \sqrt{x}$ is also $y \geq 0$ because square roots are always non-negative. 6. When the domain is zero, it means there are no input values for which the function is defined. This happens if the function has no valid inputs. 7. When the range is zero, it means the function outputs only the value zero for all inputs in its domain. 8. To summarize: - Domain is about possible inputs. - Range is about possible outputs. - Domain can be zero if no inputs are valid. - Range can be zero if the function outputs only zero. This explanation aligns with the Punjab Board class 12 curriculum concepts.