Which of the following actions correctly describes using the plug-in method for inverse proportions?

Using the plug-in method for inverse proportions involves substituting values to isolate the constant ( k ) in the equation that defines the relationship between two inversely proportional variables. In situations where two variables are inversely proportional, the relationship can typically be described by the equation ( xy = k ), where ( k ) is a constant.

To find ( k ), one would substitute the known values of ( x ) and ( y ) into the equation. This step helps in determining the constant value that describes the specific relationship between the two variables being analyzed. By isolating ( k ), it becomes clear how changes in one variable affect the other in an inverse manner.

The other choices do not address the specific process of using the plug-in method in the context of inverse proportions. Finding common factors pertains to simplifying expressions rather than finding constants in this context. The quadratic formula is used to solve quadratic equations, not directly related to inverse proportions. Converting decimals to fractions is a separate mathematical operation that does not specifically address the principles of inverse variation.