Answer:

1. Domain: {1, 2, 3}

Range: {4, 5, 6}

2. Domain: {-2, 0, 2, 4}

Range: {-4, 0, 4, 8}

3. Domain: {a, b, c, d}

Range: {x, y, z}

4. Domain: {0, 1, 2, 3, 4}

Range: {0, 1, 4, 9, 16}

In each example, the domain represents the set of input values or independent variables, and the range represents the set of output values or dependent variables. The range may or may not include all possible values depending on the specific function or relation being represented.