Chapter 3 – Linear Systems

Solving Systems Using Tables and Graphs

Section 3.1

System of Equations

•A set of 2 or more equations with the same variables

•Ex:

Solution of a System

•A set of values for variables that makes ALL the equations true.

•Ex:

•Is a solution to the above system?

Using a Graph to Find a Solution

1. Ex:

You Try

2. Ex:

Practice

3. Ex:

STEPS

1.Solve each equation for y.

2.Carefully graph each equation with a STRAIGHT line.

3.Find the point of intersection (x, y).

HOMEWORK

p. 138 #1, 2, 7-10 - graph and find the solution to each system

Warm Up (Day 2)

Graph each system to find the solution:

1. 2.

Three Possibilities…

How Can You Tell Without Graphing?

1.Solve each equation for y.

2.Compare the slopes. If they are DIFFERENT… the lines will intersect

ONE SOLUTION

3.If the slopes are the same, compare the y-intercepts. If those are DIFFERENT…the lines are parallel

NO SOLUTION

4.If BOTH slope and intercepts are the same…the lines coincide

INFINITELY MANY SOLUTIONS.

PracticeWithout graphing, determine whether the system has one solution, no solutions, or infinitely many solutions.1.

PracticeWithout graphing, determine whether the system has one solution, no solutions, or infinitely many solutions.2.

PracticeWithout graphing, determine whether the system has one solution, no solutions, or infinitely many solutions.3.

In the Graphing Calculator

•Put the two equations into Y1 and Y2.

•They MUST be solved for y!

•[2nd][CALC][5] for intersect. Hit [ENTER] 3 times, and it will calculate the point (x, y) where they intersect!

HOMEWORK (day 2)

•p. 139 #17-23 (w/o graphing, determine whether the system has 0, 1, or infinitely many solutions)

•#30, 33 (find the solution to the system using the graphing calculator)