What is the undefined value for 22=4+5x/9x−6

To find the value for which the expression \( \frac{4 + 5x}{9x - 6} \) is undefined, we need to determine when the denominator \( 9x - 6 \) equals zero.

Set the denominator equal to zero and solve for \( x \):

\[
9x - 6 = 0
\]

Add 6 to both sides:

\[
9x = 6
\]

Now, divide both sides by 9:

\[
x = \frac{6}{9}
\]

This simplifies to:

\[
x = \frac{2}{3}
\]

Thus, the undefined value is:

\[
\boxed{\frac{2}{3}}
\]