Graphing

1
Graphing

• How to create a graph and how to interpret
  different graph designs

2
Rules for plotting data

• Identify the independent and dependent variables.
• Ind. Variable
• A. the value you control / change
• B. always on the X-axis
• Dep. Variable
• A. the result of the change to the I.V.
• B. always on the Y-axis

3
Rules for plotting data (cont.)

1. Determine the range of the I.V. to be plotted
2. Decide if a (0,0) origin is a valid data point
3. Spread the data out as much as possible (each
   division on the graph paper should be the largest
   convenient unit)
4. Number and label the X-axis
5. Repeat steps 2 5 for D.V.

4
Rules for plotting data (cont.)

1. Plot the data points
2. Draw line of best fit or smooth curve DO NOT play
   connect the dots!!!
3. Give the graph a title that tells what it
   represents
4. Include any other info. that is asked (formula,
   equation, etc.)

5
Types of Graphs

• Linear Relationship
• 1. Directly proportional
• 2. Graph straight line
• 3. Equation y mx b
• m slope b y-intercept
• 4. m rise ?y
• run ?x

6
Types of Graphs (cont.)

• Linear Relationship (cont.)
• 5. Y-intercept (b) the Y value when the X
  value is 0.
• 6. When b 0, the equation becomes y mx

7
Linear Relationship Graph
8
Types of Graphs (cont.)

• Nonlinear Relationships
• A. Quadratic Relationship
• 1. Graph Parabola
• 2. Equation y ax2 bx c
• (a, b, c are constants)
• 3. if b 0 and c 0 then y ax2
• (if x gets larger, then y gets larger by the
  square of x)

9
Quadratic Relationship Graph
10
Types of Graphs (cont.)

• Nonlinear Relationships
• B. Inverse Relationship
• 1. Graph Hyperbola
• 2. Equation y a/x or xy a
• 3. As x gets larger, y gets smaller
• 4. This is an indirect relationship

11
Inverse Relationship Graph