Instead of y = mx +b, we can
write linear functions like this:
f(x) = mx + b
f(x) is read “f of x.”
This means:
The value of function f at x
It does NOT mean “f times x”
Can also use other letters
(not just f!)
Examples:
f(x) = 2x + 1
g(x) = -x – 6
h(x) = 4x – 2
When we need to evaluate a
function for a given x value, it might
say:
“Find f(3)”
- or -
“Evaluate f(x) when x = 3”
This means:
Find the output when the input is 3.
Evaluate f(x) = -4x + 7 when
x = 2.
Let g(x) = -x – 1. Find g(4).
Let f(x) = 2x – 5.
Evaluate the function when
x = -4, 0, and 3.
f(-4) =
f(0) =
f(3) =
For find the
value of x for which h(x) = -7.
For find the
value of x so that f(x) = 21.
For find the
value of x so that g(x) = -1.
To graph in function notation:
Remember: f(x), g(x), h(x) just
replace the y in y = mx + b
(0, b) is still the y-int
m is still the slope
Graph f(x) = 2x + 5
Graph:
Graph each function on the
same graph.
f(x) = 2x
g(x) = 2x + 3
h(x) = 2x – 3
What do you notice about
these 3 graphs?
The graph of f(x) + k is a
vertical translation (shift) of
the graph of f(x).
Lines have the same slope but
different y-intercepts.
Compare the graph of
g(x) = x – 3 to the graph of
f(x) = x.
Compare each graph to the
graph of f(x) = -3x:
g(x) = -3x + 4
h(x) = -3x – 5

5 4 function notation

  • 2.
    Instead of y= mx +b, we can write linear functions like this: f(x) = mx + b f(x) is read “f of x.” This means: The value of function f at x It does NOT mean “f times x”
  • 3.
    Can also useother letters (not just f!) Examples: f(x) = 2x + 1 g(x) = -x – 6 h(x) = 4x – 2
  • 4.
    When we needto evaluate a function for a given x value, it might say: “Find f(3)” - or - “Evaluate f(x) when x = 3” This means: Find the output when the input is 3.
  • 5.
    Evaluate f(x) =-4x + 7 when x = 2.
  • 6.
    Let g(x) =-x – 1. Find g(4).
  • 7.
    Let f(x) =2x – 5. Evaluate the function when x = -4, 0, and 3. f(-4) = f(0) = f(3) =
  • 8.
    For find the valueof x for which h(x) = -7.
  • 9.
    For find the valueof x so that f(x) = 21.
  • 10.
    For find the valueof x so that g(x) = -1.
  • 11.
    To graph infunction notation: Remember: f(x), g(x), h(x) just replace the y in y = mx + b (0, b) is still the y-int m is still the slope
  • 12.
  • 13.
  • 14.
    Graph each functionon the same graph. f(x) = 2x g(x) = 2x + 3 h(x) = 2x – 3 What do you notice about these 3 graphs?
  • 15.
    The graph off(x) + k is a vertical translation (shift) of the graph of f(x). Lines have the same slope but different y-intercepts.
  • 16.
    Compare the graphof g(x) = x – 3 to the graph of f(x) = x.
  • 17.
    Compare each graphto the graph of f(x) = -3x: g(x) = -3x + 4 h(x) = -3x – 5