Graphing Linear Equations

1
Graphing Linear Equations
2
Linear Equation

• An equation for which the graph is a line

3
Solution

• Any ordered pair of numbers that makes a linear
  equation true.
• (9,0) IS ONE SOLUTION
• FOR Y X - 9

4
Linear Equation

• Example
• y x 3

5
Graphing

• Step 1
• Three Point Method
• Choose 3 values for x

6
Graphing

• Step 2
• Find solutions using table

y x 3 Y X 0 1
2


7
Graphing

• Step 3
• Graph the points from the table
• (0,3) (1,4) (2,5)

8
Graphing

• Step 4
• Draw a line to connect them

9
Try These

• Graph using a table (3 point method)
• 1) y x 3
• 2) y x - 4

10
X-intercept

• Where the line crosses the x-axis

11
X-intercept

• The x-intercept has a y coordinate of ZERO

12
X-intercept

• To find the x-intercept, plug in ZERO for y and
  solve

13
Slope

• Describes the steepness of a line

14
Slope

• Equal to
• Rise
• Run

15
Rise

• The change vertically, the change in y

16
Run

• The change horizontally or the change in x

17
Finding Slope

• Step 1
• Find 2 points on a line
• (2, 3) (5, 4)
• (x1, y1) (x2, y2)

18
Finding Slope

• Step 2
• Find the RISE between these 2 points
• Y2 - Y1
• 4 - 3 1

19
Finding Slope

• Step 3
• Find the RUN between these 2 points
• X2 - X1
• 5 - 2 3

20
Finding Slope

• Step 4
• Write the RISE over RUN as a ratio
• Y2 - Y1 1
• X2 - X1 3

21
Y-intercept

• Where the line crosses the y-axis

22
Y-intercept

• The y-intercept has an x-coordinate of ZERO

23
Y-intercept

• To find the y-intercept, plug in ZERO for x and
  solve

24
Slope-Intercept

• y mx b
• m slope
• b y-intercept

25
Step 1

• Mark a point on the y-intercept

26
Step 2

• Define slope as a fraction...

27
Step 3 Numerator is the
vertical change

• (RISE)

28
Step 4

• Denominator is the horizontal change
• (RUN)

29
Step 5

• Graph at least 3 points and connect the dots