#
In this solution, how does coefficient of y becomes zero ? What is the reason that if a line is parallel to y axis , then the coefficient of y becomes zero ?

The standard equation of a line is, Ax + By + C = 0

Here if the coefficient of y i.e. B is 0 then the equation becomes Ax+ (0)y + C = 0

Now, if we take any real value of y it will not have any effect on the equation since 0 multiple with anything (real) is 0

So, what we get is

Ax + C = 0

x = -C/A

This mean irrespective of value of y, x will have a constant value, this when plot on a Cartesian Plane gives a Vertical line or a Line parallel to Y-axis.

Regards

**
**