GraphingHow to create a graph and how to interpret different graph designs

Rules for plotting data1. Identify the independent and dependent

variables.Ind. Variable:A. the value you control / changeB. always on the X-axisDep. Variable: A. the result of the change to the I.V.B. always on the Y-axis

Rules for plotting data (cont.)2. Determine the range of the I.V. to be plotted

3. Decide if a (0,0) origin is a valid data point

4. Spread the data out as much as possible (each division on the graph paper should be the largest convenient unit)

5. Number and label the X-axis

6. Repeat steps 2 – 5 for D.V.

Rules for plotting data (cont.)7. Plot the data points

8. Draw line of best fit or smooth curve DO NOT play connect the dots!!!

9. Give the graph a title that tells what it represents

10. Include any other info. that is asked (formula, equation, etc.)

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

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

Linear Relationship Graph

Types of Graphs (cont.) Nonlinear Relationships –

A. Quadratic Relationship:1. Graph : Parabola2. 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)

Quadratic Relationship Graph

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

Inverse Relationship Graph