2x+6 = 0in two variables is 2x + 0y + 6 = 0
Here, all the value of y can be taken as product of 0 and y is always 0.
x must satisfy the equation 2x+6 = 0
⇒ 2x = -6
⇒ x = -3
Thus, x = -3 and y = 0
The graph obtained will be a line parallel to Y-axis at a distance of -3 on X-axis.