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Every element of the input value is associated with one unique element of the output.

Linear function always forms a straight line.
For every x-input there is a y-output.
Each time y changes, x is either constant, decreasing or increasing.
An equation means two expressions are equal.
A function only outputs a value.
LINEAR FUNCTION FORMULA
Components of a linear function
f(x) = mx + b
dependent variable
input
slope
   y  =  f(x) mx  +  b)
independent variable
y-intercept
LINEAR FUNCTION FORMULA
Explanation of the linear function format

1)

slope

m  = 

1

1

y - y   = change y
x - x   = change x

y  =  mx + b
y - b   =  mx + b - b
y - b   =  mx
     x           x
y - b  =  m
   x

2)

y-intercept

 y = mx + b

when x = 0

 y = m(0) + b
  y = 0 + b
  y = y-intercept = b

P (x, y)

(0, b) = y-intercept

y - b

x

(a, 0) = x-intercept

P (x   , y  )

1

1

Linear Function Formula
Explanation and example of linear function

Equation Table

y

 f(x) = mx +  b

x

input       association     output

y = mx + b is the same as F(x) = mx + b, except functions emphasizes:

  • A function means for every input there is one output.

  • They have x (dependent) and y (independent) variables.

  • These variable form a relationship.

  • Each output is related to one or more inputs.​

f(x) =  1 x + 3
3

Equation Table

 f(x) = 1x/3 + 3 

x

1(0)/ 3 + 3

1(-9)/3 + 3 

1(3)/3 + 3

1(-6)/3 + 3

input       association     output

y

3

0

4

1

0

-9

3

-6

Function example:

y  =      x  +  3

 1 

3

 1 

3

f(x)  =      x  +  3

if x  =  -6

 1 

3

f(-6) =      x + 3

 1 

3

f(-6)  =       (-6)  +  3

-6

3

f(-6)  =           +  3

f(-6)  =   -2   +  3

f(-6)   =   1

6

(3, 4)

6

4

 (0, 3)

4

2

2

-2

-2

-8

-10

 (-9, 0)

-6

-4

 (-6, 1)

m
(x   -     )
 
x

1

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