1. 5-2 Slope Intercept Form
Hubarth
Algebra

2. Y-INTERCEPT- is the y-coordinate of the point where the line crosses the y-axis.
The x-coordinate of the y-intercept is always 0, so the coordinates of the y-intercept
will always be (0, y), y can be any real number.
X-INTERCEPT- is the x-coordinate of the point where the line crosses the x-axis.
The y-coordinate of the x-intercept is always 0, so the coordinates of the x-intercept
will always be (x, 0), x can be any real number.
Slope-Intercept Form
The slope-intercept form of a linear equation is y = mx + b.
m = the slope of the line.
b = the y-intercept. (0, b)

3. Ex 1 Identifying Slope and Y-intercept
What are the slope and y-intercept of y = 2x – 3?
mx + b
y =
2x – 3
Use the Slope-Intercept form.
slope, m = 2
y-intercept, b = (0, -3)

4. Ex 2 Writing an Equations5
Write an equation of the line with slope and y-intercept 4.
Use the slope-intercept form.
y = mx + b
y = x + 4 2 5
Substitute for m and 4 for b.

5. Ex 3 Writing an Equation From a Graph
Write an equation for the line.
Step 1 Find the slope. Two points
on the line are (0, 1) and (3, –1).
–1 – 1
3 – 0
slope =
= – 2 3
Step 2 Write an equation in
slope–intercept form. The y-intercept is 1.
y = mx + b 2 3
y = – x + 1
Substitute – for m and 1 for b.

6. Ex 4 Verifying a point on a Line
Determine whether (1, 2) lies on the graph of y = 3x – 1.
y = 3x – 1
(1) – 1
Substitute 1 for x and 2 for y.
– 1
Multiply.
2 = 2
Subtract.
(1, 2) is a solution.

7. Step 1 Identify the slope and y-intercept. t = 300 + 0.15s
Ex 5 Graphing Equations
The base pay for a used car salesperson is $300 per week. The salesperson also earns 15% commission on sales made. The equation t = s relates total earnings t to sales s. Graph the equation.
Step 1  Identify the slope and y-intercept.
t = s
t = 0.15s + 300  Rewrite the equation in slope intercept form.
slope y-intercept
Step 2  Plot two points. First plot a point at the y-intercept. Then use the slope to plot a second point. 15
100
The slope is 0.15, which equals Plot a second point 15 units above and 100 units to the right of the y-intercept.
Step 3  Draw a line through the points.

8. . . Practice 1. Find the slope and y-intercept of each equation
2. Write the equation of the line given the slope and y-intercept..
3. Write the equation of the line from the graph. .
(0, 1) .
(2, 2)
4. Determine whether the point lies on the line.
a. (1, 6), y = 4x -2
b. (3, -5), y = -3x + 4 No
Yes