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Reading a Function's Graph Over an Interval on the Coordinate Plane

Locating a function's value as a height above the horizontal axis at a given input, and identifying the portion of the graph that lies over a chosen interval of that axis. Covers which axis carries the input, which carries the output, what a point on the curve reports, and how the endpoints of an interval cut out a bounded piece of the picture.

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Introduction to increasing, decreasing, positive or negative intervals | Algebra I | Khan Academy

For a function y = f(x), the sign of the function (positive or negative) describes whether its graph lies above or below the x-axis over a given interval, with the function's value equal to zero at t…