3.3 Linear Functions
3.3 Linear Functions
3.3 Linear Functions
g(3)=2(3)2 +1
g(3)=2(9)+1
g(3)=19
Given f(x) = 3x - 1, find 4[f(4) – f(2)]
Given h(x) = 5+5x, find [f(4) – f(1)](-2)
3.3 Linear Functions
The student will be able to:
1. identify linear functions.
2. write equations in standard form.
3. Graph linear functions.
Indicators:
Designed by Skip Tyler, Varina High School
Vocabularies
• A linear equation is the equation of a line.
• An x-intercept is a point on the graph where y is
zero. In other words, an x-intercept is a point in the
equation where the y-value is zero.
• A y-intercept is a point on the graph where x is
zero. In other words, a y-intercept is a point in the
equation where the x-value is zero.
• Values of x for which f(x)=0 are called zeros. For a
linear function, the zero is its x-intercept.
Standard Form
Ax + By = C
A, B, and C have to be integers
An equation is LINEAR (the graph is
a straight line) if it can be written in
standard form.
This form is useful for graphing
(later on…).
Determine whether each equation is
a linear equation.
1) 4x = 7 + 2y
Can you write this in the form
Ax + By = C?
4x - 2y = 7
A = 4, B = -2, C = 7
This is linear!
Determine whether each equation is
a linear equation.
2) 2x2 - y = 7
Can you write it in standard form?
NO - it has an exponent!
Not linear
3) x = 12
x + 0y = 12
A = 1, B = 0, C = 12
Linear
Here’s the cheat sheet! An equation that is
linear does NOT contain the following:
1. Variables in the denominator
3
y 2
x
2. Variables with exponents
y x 3
2
Standard Form
x – 4y = 3
Is this equation linear?
9 4y x
2
1. Yes
2. No
Exponents are
not allowed!
Is this equation linear?
y = -3
1. Yes
2. No
Standard Form
0x + y = -3
Review of the definition.
graph 3x + y = 6
1. Solve for y: 3x + y = 6
Subtract 3x - 3x - 3x
2. Make a table
x -3x + 6 y = -3x + 6
ordered pair
-2 -3(-2) + 6 = 12 (-2, 12)
-1 -3(-1) + 6 = 9 (-1, 9)
0 -3(0) + 6 = 6 (0, 6)
1 -3(1) + 6 = 3 (1, 3)
2 -3(2) + 6 = 0 (2, 0)
5) Given the domain {-2, -1, 0, 1, 2},
3.
graph 3x
Plot the points
+ y = 6
(-2,12), (-1,9), (0,6), (1,3),
(2,0)
4. Connect the points.
Bonus questions!
What is the x-intercept?
(2, 0)
What is the y-intercept?
(0, 6)
Does the line increase or decrease?
Decrease
5) Given the domain {-2, -1, 0, 1, 2},
graph 4x + 2y = 6
Which is the graph of y = x – 4?
1. .
2. .
3. .
4. .
• P 158 36-37, 39-43 odds ( might change
due to time consuming)