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Holt Algebra 2

2-3 Graphing Linear Functions

Quiz: 2-1 to 2-5 – Fri. 1/30

HWQ #3 – Mon. 2/2

The Plan For Today

• Correct 2-1/2-2

• A few things…

• Lesson 2-3 (p.105-108)

�Determine whether a function is linear.

�Graph a linear function given two points, a

table, an equation, or a point and a slope.

• Lesson 2-4 (p.115-119)

�Use slope-intercept form and point-slope

form to write linear functions.

�Write linear functions to solve problems.

• Assignment 2-3/2-4

Holt Algebra 2

2-3 Graphing Linear Functions

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Recording L to J Results

Holt Algebra 2

2-3 Graphing Linear Functions

When you miss questions, what do you do about it?

Holt Algebra 2

2-3 Graphing Linear Functions

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Holt Algebra 2

2-3 Graphing Linear Functions

Determine whether the data set could represent a linear function.

Example 1A: Recognizing Linear Functions

x –2 0 2 4

f(x) 2 1 0 –1

+2

–1

+2

–1

+2

–1

The rate of change, , is constant .

So the data set is linear.

Holt Algebra 2

2-3 Graphing Linear Functions

The constant rate of change for a linear

function is its slope. The slope of a linear

function is the ratio , or .

The slope of a line is the same between

any two points on the line. You can graph

lines by using the slope and a point.

2

Holt Algebra 2

2-3 Graphing Linear Functions

Example 2A: Graphing Lines Using Slope and a Point

Graph the line with

slope that passes

through (–1, –3).

Holt Algebra 2

2-3 Graphing Linear Functions

Recall from geometry that two points determine a line. Often the easiest points to find are the points where a line crosses the axes.

The y-intercept is the y-coordinate of a point where the line crosses the x-axis.

The x-intercept is the x-coordinate of a point where the line crosses the y-axis.

Holt Algebra 2

2-3 Graphing Linear Functions

Linear functions can also be expressed as linear equations of the form y = mx + b. When a linear function is written in the form y = mx + b, the function is said to be in slope-intercept formbecause m is the slope of the graph and b is the y-intercept. Notice that slope-intercept form is the equation solved for y.

Holt Algebra 2

2-3 Graphing Linear Functions

Vertical and Horizontal Lines

Vertical Lines Horizontal Lines

The line x = a is a vertical line at a.

The line y = b is a vertical line at b.

Holt Algebra 2

2-3 Graphing Linear Functions

Holt Algebra 2

2-3 Graphing Linear Functions

3

Holt Algebra 2

2-3 Graphing Linear Functions

Holt Algebra 2

2-3 Graphing Linear Functions

Holt Algebra 2

2-3 Graphing Linear Functions

Holt Algebra 2

2-3 Graphing Linear Functions

Holt Algebra 2

2-3 Graphing Linear Functions

2-3

p. 109-112

23-43 odd, 52, 58-63

Today’s Assignment

2-4

p. 120-123

12-20 even, 21-26, 38, 44-46Holt Algebra 2

2-3 Graphing Linear Functions

� What did you like?� What didn’t you like?� What did you learn?� What isn’t quite clear?� ______ is awesome!� Please stop _________.� Anything else…