Pre-Calculus All-in-One For Dummies

Chapter 18

Streamlining Systems of Equations

IN THIS CHAPTER

Showing the why before the how

Taking on two-equation systems with substitution and elimination

Breaking down systems with more than two equations

Graphing systems of inequalities

Solving equations: Why do you do it? You need an answer to a question about the height of a kite. You need the answer to the question about the length and width of a garden. You need an answer about an answer! Sometimes you need one equation to solve a problem, and sometimes you need more than one equation. These instances are covered here.

Solving equations: What do you do? When you have one variable and one equation, you can almost always solve the equation for the variable. When a problem has two variables, however, you need at least two equations to solve and get a unique solution; this set of equations is called a system. When you have three variables, you need at least three equations in the system to get a single answer. Basically, for every variable present, you need a separate unique equation if you want to solve the system for its special ...