# Chapter 2 - Section 2.3 - Writing Equations of Lines - 2.3 Exercises - Page 173: 63

$x=9$

#### Work Step by Step

Lines that have an undefined slope take the form $x=a$, where $a$ is the $x-$intercept. Since the line passes throught $( 9,10 )$, then the equation is \begin{array}{l}\require{cancel} x=9 .\end{array}

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