The following are true of the constant of proportionality:

• It is represented symbolically by the variable k.


• It describes the constant ratio of two proportional quantities, usually represented with x and y such as k =
  yx
  .


• It is also known as constant of variation or unit rate.


• It describes the constant rate of change between two quantities in a proportional relationship.


• It represents the slope of the line of a graphed proportional relationship where x represents the independent variable and y represents the dependent variable.
  
  
  
  
  

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Constant of Proportionality Activity

In the equation y = 3x - 4, three is the slope in a non-proportional situation.