Warm Up1. Determine if this relation is a function.

2. Find if .

3. Find the x-intercept and y-intercept of the graph of . The graph the equation.

4. Find the slope of a line that passes through (3, 5) and (4, 1).

2.4 Writing Equations of Lines

The slope intercept form of the equation of a line is where is the ___________ and is the _____________.

Slope-Intercept Form

Option 1: Given the slope and y-intercept of a line.

Slope-Intercept Form

Option 2: Given a graph.y

x

Slope-Intercept Form

Option 3: Given the slope and point on the line.

Slope-Intercept Form

Option 4: Given two points on the line.

Try It On Your Own.

Write an equation of the line.1. .

Point-Slope FormThe point-slope form of the equation of a line is

,

where are the coordinates of a point on the line and is the slope of the line.

Point-Slope Form

Option 1: Given the slope and a point on the line.

Point-Slope Form

Option 2: Given two points on the line.

Try It On Your Own

Write an equation of the line.

1. .

Standardized TestingTests like HSAP or the COMPASS love to ask questions like this…

Which is an equation of the line that passes through (-2, 7) and (3, -3)?

A.

B.

C.

D.

Parallel Lines

How do you know if two lines are parallel?

Their SLOPES are the SAME!

and

and

ExampleWrite an equation of a line that passes through (12, 0) and is parallel to .

Write an equation of a line that passes through (0, 9) and is parallel to .

Perpendicular Lines

How do you know if two lines are perpendicular?

Their SLOPES are the NEGATIVE RECIPROCALS!

and

and

ExampleWrite an equation of a line that passes through (5, -6) and is perpendicular to .

Write an equation of a line that passes through (6, -1) and is parallel to .

Summary

Slope-Intercept Form:

Point-Slope Form:

Parallel Lines:

Perpendicular Lines:

Homework!!! YAY!

Lesson 2.4 Page 87#’s 9, 13, 15, 17-19, 23, 24 and 32