A function is a special mathematical relation in which each domain (first number of the ordered pair) has a unique corresponding range (second number of the ordered pair). A function can take any form, for example, f(x) = 5x, f(x) = x - 12. Inputting a number into the function and performing the required operations yield a point on the graph of the function. Graphically, this means that no point on the graph is directly above any other point: they may be close but never directly above one another.
Instructions
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1
Identify the horizontal or x-axis of the graph.
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2
Align the ruler so that it is perpendicular to the x-axis.
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3
Slide the ruler along the x-axis. Look for any points on the graph where the ruler intersects the graph at more that one point: The ruler will only intersect the graph at one point at a time if the graph is a function.