For what value of x is the rational expression below undefined?

check all that apply

x+8/x^2-2x-24

A. 4

B.-4

C.-6

D.-8

E. 8

F. 6

I can only guess that by x^2-2x-24 you mean the entire denominator. In cases like this is is important to use parentheses to remove any doubts. For example:

(x+8) / (x^2-2x-24).

This rational expression is undefined at any x for which the denominator, x^2-2x-24, is zero.

x^2-2x-24 factors into (x+4) (x-6). The roots are - 4 and + 6.

Thus, the given expression is undefined at {-4,6} (set notation).