What is the standard form equation of the line?

First, find the slope of the line:    m  =  (y2 - y1) / (x2 - x1)

x1 = 1     y1 = 4     x2 = 1     y2 = 2          --->     m  =  (2 - 4) / (1 - 1)  =  -2 / 0   <--- undefinded.

Looking at the graph of these two points, they lie in a vertical line.

The equation of a vertical line is  x  =  a, so the equation of this line is x = 1.