Question

Which of the following is not a function? Select all that apply.


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Answer 1

I can't see the four images you referred to. Could you re-upload them or describe each one (for example: “graph of a circle centered at (0,0) radius 2”, “mapping diagram with arrows from 1→2 and 1→3”, “set {(1,2),(2,3),(1,4)}”, “y = ±√x”, etc.)?

Meanwhile, here are the quick tests you can use to decide whether each relation is a function:

- For a graph in the xy-plane: use the vertical line test. If any vertical line intersects the graph in more than one point, it is not a function.
- For a mapping (arrow) diagram: if any input element has arrows to more than one output, it is not a function.
- For a list of ordered pairs: if any first coordinates repeat with different second coordinates (e.g., (1,2) and (1,3)), it is not a function.
- For an equation: solve for y. If for some x there are multiple y values (e.g., circle x^2 + y^2 = 1 gives two y for many x), it is not a function; if each x gives exactly one y (e.g., y = x^2) it is a function.

If you upload the images or describe each option A–D, I’ll mark which ones are not functions and explain briefly why.