Answer: Choice D
Yes, because every x-value corresponds to exactly one y-value.
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Further explanation:
If the table had two points such as (10,1250) and (10,1300), then it would lead to "not a function" because x = 10 corresponds to more than one y value.
Instead, each x input leads to exactly one y output. Therefore, we have a function. You can use the vertical line test to confirm visually.
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In short,
- If x values repeat ---> not a function
- If x values don't repeat ---> we have a function
The y values can repeat, but the function wouldn't be one-to-one (aka injective). In this case, the y values do not repeat so this function is one-to-one.