The standard form of a linear equation is: color(red)(A)x + color(blue)(B)y = color(green)(C)
Where, if at all possible, color(red)(A), color(blue)(B), and color(green)(C)are integers, and A is non-negative, and, A, B, and C have no common factors other than 1
Horizontal Line
A horizontal line has the same value for y for each and every value of x. Therefore, because the y value for the point in the problem is -8 the equation for this line is:
y = -8
To put this in standard format, the coefficient for x is 0 and the coefficient for y is 1 giving:
color(red)(0)x + color(blue)(1)y = color(green)(-8)
Vertical Line
A horizontal line has the same value for x for each and every value of y. Therefore, because the x value for the point in the problem is -1 the equation for this line is:
x = -1
To put this in standard format, the coefficient for y is 0 and the coefficient for x is 1 giving:
color(red)(1)x + color(blue)(0)y = color(green)(-1)