When a system of two linear equations is consistent, which of the following must be true?

Question

Its solution is the empty set.
Its solution set consists of at least one ordered pair.
Its solution set consists of exactly one ordered pair.
Its solution set consists of infinitely many ordered pairs.

Answer 1

If the lines are the same (the graphs intersect at all points), the system is a consistent system of linear equations and the equations are dependent. That is, any solution of one equation must also be a solution of the other, so the equations depend on each other.