What is the x-coordinate in an ordered pair (x, y)?

The x-coordinate in an ordered pair (x, y) represents the horizontal position on a Cartesian coordinate plane. In this system, the first value, or x-coordinate, indicates how far along the horizontal axis an point is located from the origin (0,0). If the x-coordinate is positive, it is positioned to the right of the origin; if it is negative, it is to the left. Understanding this is crucial for graphing points and interpreting their positions in relation to one another in a two-dimensional space.

The other options pertain to different aspects of coordinate geometry: vertical position relates to the y-coordinate, the slope is a measure of the steepness of a line, and area pertains to two-dimensional figures which does not directly relate to the positioning of points in the coordinate plane.