To determine the x-values for which the function \( y = (x - 1)^2 - 4 \) is increasing, we need to analyze the vertex and the general behavior of a parabola.
The vertex of the parabola is at the point \( (1, -4) \). For a parabola that opens upward, the function is decreasing to the left of the vertex and increasing to the right of the vertex. Therefore, the function begins to increase after reaching the vertex.
Since the vertex is at \( x = 1 \), the function is increasing for all \( x \) values greater than \( 1 \).
Thus, the answer is: \( (x | x > 1) \).