how do i sketch a graph using the formula z = -1 (label an intercept and another point)?

y-intercept: x = 0, so y = -1
For another point, choose, e.g., x = 1; again, y = -1
The graph is a straight line, which is horizontal.
(So there is no x-intercept.)

Like this:
Graph: https://www.desmos.com/calculator/r8lquxuyz1

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