How to get a equation of a line in slope intercept form with the rate of change as undefined?

Linear equation:   x = -1

Step-by-step explanation:

Vertical lines have undefined slopes, as represented by the linear equation, x = a, where the x-intercept is (a, 0).

A vertical line has undefined slope because all points the line have the same x-coordinate.  Since any two points on a vertical line have the same x-coordinate, slope cannot be computed as a finite number.  The equation cannot be expressed in slope-intercept form because it has an undefined slope.  

Therefore, since you're given the point, (-1, 4), then it means that your equation will be: x = -1.

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