Question

Are two lines coincident,if they have a common point?

Answer 1

Please see the explanation.

Explanation:

No, when two lines coincide, the equations have the same graph, one line lie on top of the other. Coincident lines have all their points in common, so every solution of one equation is a solution of the other, such system have infinite number of solutions.
On the other hand when two lines have only one common point, they intersect only once and the point of intersection i.e, common point is the only solution of the system.