The question says to find all ninpermissable replacements that make the radical expressions undefined, I have an awnser but not sure if I am doing it correct.
it is y the second power minus 16, over y plus 1.

y^2 -16/y+1

The nonpermissable replacements for what?

the nonpermissable replacements that make the radical expression undefined?
y^2 -16/y+1

Well, y = -1 would be non permissible, that's the only one I can see.

Does that agree with your answer?

Yes thank you

Could you help me with a couple more questions?

Sure post them in new threads, that's what we're here for.