Domain asks for any restrictions on the x-value and the range asks for any restrictions on the y-value.
Let's tackle this one at a time.
Domain: We're dealing with a quadratic function or a parabola, so usually there wouldn't be any restrictions on the x-value. When you graph out this parabola, you can see that the x-values will continue to grow to infinite and negative infinite.
Hence, there are no restrictions for the domain, and it would be all real values.
Range: Now, based on the graph, there is definitely a point at where the graph doesn't exist anymore. For a concave up or down, the range would always be greater or less than the x-value of the vertex. In this case, we have a concave up parabola, and as such, we would have a y-value that exists for when y ≥ -3