30:T4d2,

Relation

For example, {(1, 2), (3, 4), (1, a), (5, r)} is a relation. So is the set {(x, y): y = x²}; this is the set of all ordered pairs (x, y) for which y = x².

Ellipse centered at (2,1) with equation (x-2)²/9 + (y-1)²/4 = 1, with labeled points (-1,1), (2,3), (5,1), (2,-1).

See also

Function, graph

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