Bell Ringer
Take the following equations and find slope, x­intercept, y­intercept, and graph
1. 3x+5y=­20
2. 4y=­2x+12
3. x­y=0
4. x=­2
1
Review of Slope­Intercept Form
The slope­intercept form of a linear equation is y = mx + b.
m represents the slope
b represents the y­intercept
2
Review of Slope­Intercept Form
Name the slope and y­intercept of each equation:
y = ­4x + 3
y = 5 – x
8x + y = 4x ­ 2y =10
y = x
y = 5
3
Write the equation of a line given...
1.
2.
3.
4.
5.
Slope and y­intercept
Graph
Slope and one point
Two points
x ­ and y­intercepts
4
• Find the Equation of the Line
• Given the Slope and y­intercept
• Substitute m and b into y = mx + b
m = ­3, b = 1
m = ­2, b = ­4
m = 0, b = 10
m = 1, b = 0
m = 0, b = 0
5
• Find the Equation of a Line
• Given the Graph
• Find the y­intercept from the graph.
• Count the slope from the graph.
• To write the equation of the line, substitute the slope and y­intercept in the slope­intercept form of the equation.
6
Example 1
• b = ­3
• m = 7
Example 2
• b = 1
• m = 8
Example 3
9
• Find the Equation of a Line
• Given the Point and the Slope • Use the Point­Slope Formula:
• is the given point • Substitute m and into the formula
10
Example
• Write the equation of the line with slope = ­2 and passing through the point (3, ­5).
11
• Find the Equation of the Line
• Given Two Points
• Calculate the slope of the two points.
• Use one of the points and the slope to substitute into the Point­Slope formula.
12
Example
• Write the equation of the line that goes through the points (3, 2) and (5, 4). 13
• Find the Equation of the Line
• Given the x­ and y ­ intercepts • Write the intercepts as ordered pairs.
• The x­intercept 4 • The y­intercept ­2
• Calculate the slope.
• Substitute the slope and the y­intercept (b) into the slope­intercept formula.
14
Example
Write the equation of the line with x­intercept 3 and y­intercept 2.
15
16