Question

Which represents all the values of x that make the rational expression 2x-4 over x-5 undefined?

Answer 1

For this case we have the following expression:

$\frac {2x-4} {x-5}$

By definition, we have the expression undefined when the denominator is 0.

So:

$x-5 = 0$

Adding 5 to both sides of the equation:

$x-5 + 5 = 5\\x = 5$

Thus, the expression is undefined when $x = 5.$

Answer:

Option B