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Function or Not a Function?VERTICAL LINE TEST - A function must pass the vertical line test if graphed. If you can draw a vertical line anywhere on the graph, and the graphed function doesn't cross that vertical line more than once, then it is a function.
LOOKING AT A TABLE, ORDERED PAIRS, MAPPING, ETC - A function is a relation in which "each element of the domain is paired with only one element of the range." That means each x-value can only be paired with one y-value. Check the x-values. If they are all different, it IS a function. If they are not all different, we need to then check which y-values they are with. If the same x-value is paired with the same y-value, then it is still a function. If the same x-value is paired with more than one y-value, then it is NOT A FUNCTION!!! |