UPSC NDA I 2016 Mathematics Solved Paper

Concept:A line parallel to the $y$-axis has a constant $x$-coordinate.Explanation:The point of intersection of the given lines is $(1, -2)$ (obtained from the previous part of the problem).Any line parallel to the $y$-axis has an equation of the form $x = c$, where $c$ is the $x$-coordinate of every point on the line.Since the required line passes through $(1, -2)$, its $x$-coordinate must be $1$.Thus the equation is $x = 1$.Writing this in standard linear form gives $x - 1 = 0$.Answer:$x - 1 = 0$ (Option B)