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💵principles of macroeconomics review

Perfectly Horizontal Line

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

A perfectly horizontal line is a line that runs parallel to the x-axis, with a constant y-coordinate value. It represents a scenario where a variable is completely unresponsive to changes in another variable, exhibiting the most extreme form of inelasticity.

5 Must Know Facts For Your Next Test

  1. A perfectly horizontal line has a constant y-coordinate value, indicating that the variable on the y-axis is completely unresponsive to changes in the variable on the x-axis.
  2. In the context of the polar cases of elasticity, a perfectly horizontal line represents the case of perfect inelasticity, where the quantity demanded or supplied does not change at all in response to changes in price.
  3. The concept of a perfectly horizontal line is closely related to the idea of constant elasticity, where the elasticity of a variable remains the same regardless of the magnitude of the change in the other variable.
  4. A perfectly horizontal line has a price elasticity of demand or supply equal to 0, indicating that the variable on the y-axis is completely unresponsive to changes in the variable on the x-axis.
  5. The perfectly horizontal line is a theoretical concept used in economic analysis to understand the extreme cases of elasticity and the factors that influence the responsiveness of variables to changes in other variables.

Review Questions

  • Explain how a perfectly horizontal line relates to the concept of perfect inelasticity in the context of the polar cases of elasticity.
    • A perfectly horizontal line represents the case of perfect inelasticity, where the quantity demanded or supplied does not change at all in response to changes in price. This means that the variable on the y-axis, such as quantity, is completely unresponsive to changes in the variable on the x-axis, which is typically price. The price elasticity of demand or supply in this case would be 0, indicating that the variable is not affected by changes in the other variable.
  • Describe the relationship between a perfectly horizontal line and the concept of constant elasticity.
    • The concept of a perfectly horizontal line is closely related to the idea of constant elasticity, where the elasticity of a variable remains the same regardless of the magnitude of the change in the other variable. In the case of a perfectly horizontal line, the elasticity is constant and equal to 0, indicating that the variable on the y-axis is completely unresponsive to changes in the variable on the x-axis. This constant and extreme form of inelasticity is a key characteristic of the perfectly horizontal line and its relationship to the concept of constant elasticity.
  • Analyze the implications of a perfectly horizontal line in economic analysis and decision-making.
    • The perfectly horizontal line is a theoretical concept used in economic analysis to understand the extreme cases of elasticity and the factors that influence the responsiveness of variables to changes in other variables. This concept has important implications for decision-making, as it helps economists and policymakers identify situations where a variable is completely unresponsive to changes in another variable. This information can be used to inform pricing strategies, resource allocation, and policy decisions that aim to achieve specific economic outcomes. Understanding the properties and implications of a perfectly horizontal line is crucial for developing a comprehensive understanding of the principles of microeconomics and their practical applications.