Is x^2+y^2=5 a function? why or why not?

No.

Step-by-step explanation:

A function must past the Vertical Line Test. We know that our equation x² + y² = 5 is a circle, and so some x-values have the same y-values, etc. Since not every x-value has its own y-value, our equation is not a function.

We can see this using a graph:

Since the vertical line test passes 2 points with the same x-value, it is not a function.

it would open into a square depending on the type of envelope i’m not sure about the second part