ALGEBRA 1 CCGraphing and Writing Equations in Slope-Intercept Form

• The three forms of writing a linear equation that we will cover this week

• Slope-Intercept form

• Standard Form

• Point-Slope Form

y mx b

Ax By C

1 1y y m x x

Example 1• Write an equation of the line shown

Example 2• Write an equation of the line that passes through the

points (4, -2) and (-2, 2)

Example 3• Write the equation of the line that passes through the

point (-4, -9) and has a slope of 2.

Graphing a Linear Equation• Step 1: Rewrite the equation in slope-intercept form (if

necessary).• Step 2: Identify the slope and y-intercept• Step 3: Plot the y-intercept• Step 4: Use the slope to plot a second point and then

draw a line through the two points.

• It is optional, but highly recommended to draw more than two points to graph a linear equation

Example 4 & 5• Identify the slope and y-intercept of the line with the given

equations and then graph the equations.

4) 5) 4x – 3y = 1514

2y x

Example 6• Write an equation for the linear function f with the given

values

f(6) = -4, f(9) = -9

• Two lines in the same plane are parallel if they do not intersect. • Parallel lines have the same slope.

• Two lines in the same plane are perpendicular if they intersect to form a right angle. • Perpendicular lines have slopes that are opposite reciprocals.

Example 7

• Tell whether the following graphs are parallel, perpendicular, or neither.

y = 2x + 4

4x + 2y = 12

Example 8

• Tell whether the following graphs are parallel, perpendicular, or neither.

3x + 4y = 24

-4x + 3y = 20