Chapter 3 Quiz
Study Guide
Scheduled for: Monday, November 7
th
Topics on Quiz:
-Graph a line making a table
-Slope-Intercept Form (lesson 4)
-Graph a Line Using Intercepts (Lesson 5)
Graph a Line by Making a Table
Example: Graph the function by creating a table:
Y = -2x - 3
Step 1: Pick values for “x” → -1, 0, 1, 2
x
y
-1
0
1
2
Step 2: Substitute the values for x into the equation: y= -2x - 3
-2(-1) - 3
2-3 =
-1
-2(1) - 3
-2-3 =
-5
-2(0) -3
0 - 3=
-3
-2(2) - 3
-4-3 =
-7
Step 3: Complete the table:
x
y
-1
-1
0
-3
1
-5
2
-7
Step 4: Graph the ordered pairs (x, y) → (-1, -1), (0, -3), (1, -5), (2, -7)
Slope-Intercept Form
Example:
Example:
State the slope and the y-intercept of the graph of the equation y = -4x
Slope = -4 and Y-intercept = 0
Graphing an Equation using the slope and y-intercept
Step 1: Identify the y-intercept (b) and graph it on the coordinate plane- it should be
on the y-axis!
Step 2: Identify the “m” or the slope and use as your MOVING DIRECTIONS to plot
a second point – Slope is a Rise/ Run from the Y-intercept Point to the 2nd point
Step 3: Connect the dots!
y = 2x + 2 (start at 2)
(slope = up two, right 1)
y = x – 1 (start at -1)
(slope = up 1, right 1)
Lesson 5 – Graph a Line using Intercepts
Find the x and y intercept
*If your equation is in y=mx + b form already you can skip to step 2!
Step 1: Plug “0” in for “y” to find your X-Intercept (2 Step Equation)
Step 2: Plug “0” in for “x” to find your Y-Intercept (2 Step Equation)
Step 3: Connect the dots!
y = -2x + 8
Step 1: *Already have a y-intercept (“b”) = +8
Graph has interval of 2’s
Step 2: Plug in “0” for y to find “x”
0 =-2x + 8
-8
-8
-8 =-2x
-8 =-2x
-2
-2
X=4
15x + 20y = 1,800
Step 1: Plug in “0” for x to find “y”
15(0) + 20y = 1,800
20y = 1,800
20
20
Y = 90
Step 2: Plug in “0” for y to find “x”
15x + 20(0) = 1,800
15x = 1,800
15
15
X = 120
Graph has interval of 30’s
Finding x and y-intercepts from a graph:
Example: State the x and y intercepts from the graph:
(Look to see where the line crosses the x and y axes)
The x-intercept is at the point (2, 0)
The y-intercepts is at the point (0, 4)
X-intercept = 2 or (2, 0)
Y-intercept = 4 or (0, 4)
Interpreting x and y intercepts from word problems: