Objectives 

• Identifying the Relevant Variables

• Constructing Equations 

• Solving Equations and Checking Solutions

Examples

• Example 1

• Example 2

• Example 3

• Example 4

Remember, our main goal in this section is to construct an equation which describes the relationships among the relevant quantities in a given problem.

In many cases, we can describe the important relationships by using known formulas.

For example, 


• If a problem involves basic geometric shapes (squares, rectangles, circles, etc.), we can use known formulas for perimeter, area, volume, etc.
  
 
• If a problem involves a right triangle, we can use the Pythagorean Theorem.
  
 
• If a problem involves an object moving with a constant speed, we can use the formula:    distance = (rate)(time)

The best way to learn how to decide which formulas can be used in a given problem is to practice, practice, practice as many problems as you can.

You should also study the details of step-by-step solutions to a wide variety of sample problems.

In fact, the more sample problems you can study and understand, the more resources you will have when attacking a new problem.