Quick Graphs of Linear Equations
Lesson 2.4
Warm-up
 6 y  3x  12
1
y  x2
2
1.
Solve for y: 3x – 6y =12
2.
Ben is making wooden toys for the next arts and crafts sale. Each toy costs Ben
$1.80 to make. If he sells the toys for $3.00 each, how many will he have to sell
to make a profit of exactly $36.00 ?
A. 12
B. 20
C. 30
D. 60
E. 108
3.
Phillip charged $400 worth of goods on his credit card. On his first bill, he was
not charged any interest, and he made a payment of $20. He then charged
another $18 worth of goods. On his second bill a month later, he was charged 2%
interest on his entire unpaid balance. How much interest was Phillip charged on
his second bill?
A. $8.76
B. $7.96
C. $7.60
D. $7.24
E. $6.63
Goal: Use slope-intercept form and standard form to
Slope
y-intercept
graph equations
y = mx +b
Step 1: Write the equation in slope-intercept form by solving for y.
Step 2: Find the y-intercept and plot the corresponding point on the y-axis
Step 3: Find the slope and use it to plot a second point on the line.
Step 4: Draw a line through the two points.
1
Example 1: Graph y  x  3
2
y-intercept: -3
Slope:
½
Example 2: Graph
y  3x
y  3x  0
y-intercept: 0
Slope:
3
3=
1
2
Example 3: Graph y  x  2
3
y-intercept: 2
Slope:
2

3
2
y  x2
3
Goal: Use standard form to graph equations.
Ax + By = C
Step 1: Write the equation in standard form.
Step 2: Find the x-intercept by letting y = 0 and solving for x. Plot the point.
Step 3: Find the y-intercept by letting x = 0 and solving for y. Plot the point.
Step 4: Draw a line through the two points.
Example 1: Graph 2 x  3 y  12
x-intercept:
2 x  12
x6
y-intercept:
3 y  12
y4
Example 2: Graph
2x  y  4
x-intercept:
2x  4
x2
y-intercept:
y4
y  4
Graph Each of the following:
2 x  3 y  12
x y 4
3x  y  6
x  2y  6
Assignment
Pages 90-94
17-37 (odds)