Question

HELP.... please??????????????

Answer 1

Answers:

Functions

• y = -x+11
• y = 2x^2-6x+4
• y = -7

Not functions

• x = 3
• x^2+y^2 = 81
• y^2 = -5x-12

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Explanation:

A function is possible if and only if any given x input leads to exactly one y output.

For something like x^2+y^2 = 81, we can see that x = 0 leads to either y = 9 or y = -9. So this would not be a function. We would need x to pair with only y value to have it be a function.

We have the same thing going on with y^2 = -5x-12 as well.

For anything of the form x = k, where k is any real number, this is also not a function. We have one single input only and it leads to infinitely many outputs. So in a sense, this is even worse compared to the other examples.

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In summary, we have these three non-functions:

• x = 3
• x^2+y^2 = 81
• y^2 = -5x-12

Everything else is a function. You can use the vertical line test as a visual way to check.