Give the geometric representations of 2x + 9 = 0 as an equation
(1) in one variable
(2) in two variables
(1) In one variable, 2x + 9 = 0 represents a point as shown in the following figure.
(2) In two variables, 2x + 9 = 0 represents a straight line
passing through point
(−4.5, 0) and parallel to y-axis.
It is a collection of all points of the plane, having their
x-coordinate as 4.5.