Question 604864
A rational expression is undefined when and only when its denominator is zero,
because division by zero is not defined.
{{{(-17)/(-18x)}}} is undefined when and only when {{{-18x=0}}}
That only happens when {{{highlight(x=0)}}}
For any other value of x, {{{-18x}}} is not zero and the rational
expression {{{(-17)/(-18x)}}} is defined (It has a value).