Two lines are COINCIDENT if their graphs lie exactly on top of each other. Every ordered pair that is part of one graph is also part of the other.
A system of equations with a solution is a CONSISTENT system.
Equations of a system which have the same graph (because they are different forms of the same equation) are called DEPENDENT equations.
The intersection (or solution) of a system of linear inequalities is sometimes called the FEASIBLE REGION of the system.
An INCONSISTENT system of equations is a system with no solution.
The INTERSECTION of sets of points in the plane is the set of points common to all the sets. A point is in the intersection if and only if it is in every one of the original sets.
The SOLUTION of a system of linear equations includes all the ordered pairs that make all the equations of the system true at the same time.
Solving a system of linear equations by addition (as in section 7.2) is also called solving the system by ELIMINATION.
In the SUBSTITUTION METHOD for solving a system of linear equations, one equation is used to write one of the variables in terms of the other. The for- mula is substituted in the other equation, which is solved for the other variable.
A SYSTEM OF EQUATIONS consists of two or more equations with the same variables.
A SYSTEM OF LINEAR EQUATIONS consists of two or more linear equations with the same variables.
A SYSTEM OF LINEAR INEQUALITIES consists of two or more linear inequalities with the same variables.
