It's true that matched forces can:

* Cause a change in motion if they are unbalanced: If two forces acting on an object are equal in magnitude but opposite in direction, they cancel each other out. This results in no net force, and the object will remain at rest or continue moving at a constant velocity.

* Cause a change in motion if they are unbalanced: If two forces acting on an object are not equal in magnitude or direction, there will be a net force. This net force will cause the object to accelerate, meaning its velocity will change.

However, it's not always true because:

* Matched forces can maintain motion: If two forces are equal and opposite, they can keep an object moving at a constant velocity. This is the basis of Newton's First Law of Motion (inertia). Think of a car traveling at a constant speed on a straight road. The force of the engine pushing forward is balanced by the force of friction and air resistance.

Key Point:

The change in motion is determined by the net force. If the forces are balanced, there's no net force, and no change in motion. If the forces are unbalanced, there is a net force, and a change in motion will occur.