Given:
The equation of line is

The perpendicular line intersect the y-axis at (0,-1).
To find:
Equation of perpendicular line.
Solution:
Point slope form of a line is
, where m is slope.
We have,

Thus, the slope of this line is
.
Product of slopes of two perpendicular lines is -1.
Let the slope of perpendicular line is
. Then,



Slope of perpendicular line is 2 and it passes through (0,-1). So, the equation of perpendicular line is



Therefore, equation of perpendicular line is
.