Lesson 4A: Simplifying Rational Expressions
Who uses rational expressions?
HVAC refers to heating, ventilation, and air conditioning. It is important in the design of buildings where temperature and humidity are controlled.
Designers of HVAC systems must determine the volume of air in the building they are designing or renovating.
For example, Edmonton's Muttart Conservatory is a pyramid. To find its volume, V, an HVAC designer would use the rational expression 
Sports equipment must undergo testing to be approved by the Canadian Standards Association.
Pads and helmets must withstand the impact of a puck travelling at speeds of 150 km/h or more.
Manufacturers must determine the velocity of the puck as it hits the helmet or pad being tested. The velocity, v, of an object is found using the rational expression 
Light bulbs are rated in terms of the electrical energy they use. Standard light bulbs are being replaced with designs that are more energy efficient. These new bulbs use less energy to produce the same amount of light.
The Canadian Office of Energy Efficiency encourages homeowners to control electricity costs by using ENERGY STAR lighting products.
To find the power, P, used by a light bulb, you can use the rational expression 
After seeing some examples of how people use rational expressions, likely you are beginning to understand the idea of a rational expression. You can see if your idea is accurate on the next page when Training Camp begins.
By the end of this lesson, you should be able to
explain the reason a value is non-permissible for a given rational expression find the non-permissible values for a rational expression simplify a rational expression
