Applications of Rational Functions: Apply It

  • Solve applied problems involving rational functions.
  • Solve rational inequalities.

Home Solar Panel Efficiency Analysis

Jake recently installed a solar panel system on his Phoenix home and wants to optimize its performance. His daily energy efficiency [latex]E(h)[/latex] (as a percentage of maximum theoretical output) depends on the number of peak sunlight hours [latex]h[/latex] according to:

[latex]E(h) = \frac{90h - 180}{h + 4}[/latex]

Solar Efficiency Analysis

Jake’s goal is to achieve at least 60% efficiency to make his monthly electricity bill negative (meaning he sells more energy back to the grid than he uses). This means he needs to solve the rational inequality:

How to: To test signs in rational inequalities:

  1. Pick a test point from each relevant interval
  2. Substitute into the simplified expression
  3. Determine if the result is positive or negative
  4. Include intervals where the expression satisfies the inequality