Question 34 • Algebra II
A graph represents a function if every vertical line crosses it at most once, so each x-value has only one y-value. In A, the curved and straight pieces meet at (1, 0.5), and the graph gives one y-value for each x. The circle in B and the right-opening parabola in C fail the vertical-line test, and D has two points with x = 4.
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