Question

Which of the following values of x makes the rational expression below undefined? x+9———3-x

Answer 1

We want to find the values where the following expression is undefined:

`(x+9)/(3-x)`

A rational expression is undefined when the denominator is equal to zero, then, the solution for the following equation is our answer:

`3-x=0`

Solving for x, we have:

`\begin{gathered} 3-x=0 \\ 3-x-3=-3 \\ -x=-3 \\ x=3 \end{gathered}`

The expression is undefined at x = 3. The answer is option B.