An equation can be written in the form x = a, where a is a fixed number. What kind of line does this equation graph?

1. The rule for this equation form states directly that x equals a graphs as a vertical line. 2. Every point on this line shares the same x-value while y can be anything, which is what makes it vertical rather than horizontal or diagonal. 3. A straight line described this simply cannot be curved. _Source: OpenStax Prealgebra (CC BY 4.0), Ch 11 "Graphs", section 11.2 Graphing Linear Equations_