Question

For what value of x would the expression below be undefined? 2x − 15 x + 9

Answer 1

Hey there!

I'm assuming your expression is actually $\frac{2x - 15}{x + 9}$. If it's not, let me know and I'll be happy to help you out further. 

If x were equal to –9, your expression would be undefined. If you solve it with this value plugged in for x, you will get the following: 

$\frac{2x - 15}{x + 9}$

$\frac{2(-9) - 15}{(-9) + 9}$

$\frac{-18 - 15}{0}$

$\frac{-33}{0}$

$error$

You can't divide anything by zero. This expression would be undefined if x were –9 since it makes the denominator zero. Therefore, x ≠ –9. 

Hope this helped you out! :-)