Answer:
... be identical.
Explanation:
The number of solutions is the number of points where the graphs intersect. If they intersect in an infinite number of points, chances are they are identical graphs.
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One can conceive of systems of equations in which the number of solutions may be infinite, but the system is not dependent. For example, one graph may oscillate periodically about the other one. y=0 and y=sin(x) is a system with an infinite number of solutions, for example.
If the system of equations is restricted to linear equations, then the only way the system will have infinite solutions is if the equations are dependent and the graphs identical.