Justify the following statement. The law of conservation of linear momentum, as applied to a single particle, is equivalent to Newton's first law of motion.

Law of conservation of linear momentum states that, in an isolated system (no external force), the algebraic sum of momenta of bodies, along any straight line, remains constant and is not changed due to their mutual action and reaction on each other.
Newton’s First Law of motion states that, everybody continues in its state of rest or of uniform motion in a straight line unless it is compelled by some external force to change that state. Therefore, without any external force, if the body is at rest, it will remain at rest. If the body is moving with constant velocity, it will continue to do so.
As the body moves with a constant velocity, its mass remains constant in the entire motion. This shows that the product of the two constants that is mass and velocity remain constant. Linear momentum is the product of the mass and velocity. Thus, the law of conservation of linear momentum, as applied to a single particle, is equivalent to Newton’s first law of motion.