Question

I'm having some trouble with this question: Find a value(s) that makes the expression y^2 - 16/ y^2 - 16 undefined.
I know that for an expression to be undefined that the denominator must be 0, so I thought -8^2, but that would just result in 16 + 16. I'm really confused and my textbook didn't have any problems like this one.

Answer 1

I meant 4^2

Answer 2

I meant -4^2 not -8^2

Answer 3

(y^2 - 16)/(y^2 - 16) Now since both expressions are the same, set one equal to zero and solve for y. by the way in your explanation you multiplied by 2, but I think you meant to square it instead. I can check your answer if u reply it as well

Answer 4

Im so sorry, again, I meant to write y^2 - 16/ y^2 + 16.

Answer 5

same rules apply solve for the denominator by setting equal to zero, if that doesnt work ill try working it too

Answer 6

Ohhh. I started thinking back to other problems I've done, and I believe that y=4i?

Answer 7

Yes that sounds right.

Answer 8

yes, but also y = -4i

Answer 9

(y^2-16)/(y^2-16) = (y+4)(y-4)/(y+4)(y-4).
Let y + 4 = 0, Y = -4.
Let y-4 = 0, Y = 4.

When Y = -4, (-4+4)(-4-4)/(-4+4)(-4-4) = (0)(-8)/(0)(-8) = 0/0 = undefined.
When Y = 4, Repeat the above operations.