A difference quotient is an expression that represents the ...
[Pages:8]16-week Lesson 19 (8-week Lesson 15)
Difference Quotient
A difference quotient is an expression that represents the difference
between two function values divided by the difference between two
inputs. This is an extension of the slope formula from Lessons 16 and 17 ( = ), when we found the change in (or the difference between two values) and divided by the change in . Now we will find the difference between two function values, divided by the difference between two
inputs:
() ( + ) - () = ( + ) -
By combining like terms in the denominator, we get the following simplified form of a difference quotient:
() ( + ) - ()
=
Difference Quotient:
- a fraction (or quotient) containing the difference of two functions
values in the numerator, and the difference of two inputs in the
denominator
o
(+)-()
o the input could be replaced with a numeric value or another
expression
Our focus when working with difference quotients in this class is to simplify them. To do so, I prefer to follow the step-by-step procedure which is demonstrated on the next page, but you are welcome to use another method if you choose.
1
16-week Lesson 19 (8-week Lesson 15)
Difference Quotient
Example 1: Given () = 5 - 2, find the difference quotient (+)-().
Steps for Simplifying a Difference Quotient:
1. find the first function value o in Example 1 I find ( + ) by replacing in the function () = 5 - 2 with the expression +
( + ) = 5( + ) - 2
5 + 5 - 2
2. find the second function value o I find () by replacing in the function () = 5 - 2 with the expression
() = 5 - 2
3. find the difference between the two function values o I find ( + ) - () by taking the two function values from
steps 1 and 2 and subtracting them
( + ) - () = 5 + 5 - 2 - (5 - 2)
5 + 5 - 2 - 5 + 2
5
4. divide the difference by the expression o since a difference quotient is a fraction, be sure to simplify completely by factoring and canceling common factors
(+)-() = 5
2
16-week Lesson 19 (8-week Lesson 15)
Difference Quotient
Example 2: Given () = -2 - + 7, find the difference quotient
(3+)-(3).
a. (3 + ) = -(3 + )2 - (3 + ) + 7
Notice that after
= -(3 + )(3 + ) - 3 - + 7
replacing with 3 + in the function , we
= -(9 + 6 + 2) - 3 - + 7 basically do addition, subtraction, and
= -9 - 6 - 2 - 3 - + 7 multiplication with
= - - -
polynomials, just like we've already done in Lesson 5.
b. (3) = -32 - 3 + 7 = -9 - 3 + 7
Be aware on part b. that -32 is the same as -1 32, which is why
= -
it simplifies to -9.
c. (3 + ) - (3) =
d.
(3+)-(3)
=
3
16-week Lesson 19 (8-week Lesson 15)
Difference Quotient
Example 3: Given the function () = 2 - 3, find the difference quotient (+)-().
Steps for Determining the Value of a Difference Quotient: 1. find the first function value
( + ) = 2( + ) - 3
( + ) = 2 + 2 - 3 2. find the second function value
() = 2 - 3
3. find the difference between the two function values ( + ) - () = 2 + 2 - 3 - (2 - 3) ( + ) - () = 2 + 2 - 3 - 2 + 3 ( + ) - () = 2
4. divide the difference by the expression
( + ) - () 2
=
4
16-week Lesson 19 (8-week Lesson 15)
Difference Quotient
Again, I prefer to break difference quotients into smaller pieces in order to simplify them, but you do not have to. You can go through and simplify difference quotients by leaving them as one single expression the entire time, as demonstrated in the next example.
Example 4: Given the function () = -52 + 10, find the difference quotient (+)-().
( + ) - () -5( + )2 + 10( + ) - (-52 + 10)
=
-5( + )( + ) + 10 + 10 + 52 - 10
-5(2 + 2 + 2) + 10 + 10 + 52 - 10
-52 - 10 - 52 + 10 + 10 + 52 - 10
-10 - 52 + 10
- - +
When simplifying difference quotients, use whichever procedure makes the most sense to you.
5
16-week Lesson 19 (8-week Lesson 15)
Difference Quotient
Example
5:
Given
the
function
()
=
1 3
2
+
5,
find
the
difference
quotient (-2+)-(-2).
As stated before, there is a lot of review from
(-2 + ) = 1 (-2 + )2 + 5(-2 + )
3
Lesson 5 when simplifying a
(-2
+
)
=
1 3
(-2
+
)(-2
+
)
-
10
+
5
(-2 + ) = 1 (4 - 4 + 2) - 10 + 5
3
(-2 + ) = 4 - 4 + 1 2 - 10 + 5
33
3
(-2 + ) = 1 2 + 11 - 26
3
3
3
(-2) = 1 (-2)2 + 5(-2)
3
(-2) = 1 (4) - 10
3
difference quotient. As shown in Example 5 on the left, we have to multiply binomials and use the distributive property to find the function value (-2 + ).
We also have to combine like terms to simplify that function
(-2) = 4 - 10
3
value as much as possible by adding and
(-2) = - 26
3
subtracting terms.
(-2 + ) - (-2) = 1 2 + 11 - 26 - (- 26)
3
3
3
3
And finally, when simplifying the
(-2 + ) - (-2) = 1 2 + 11 - 26 + 26
3
3
33
quotient, I broke the two terms in the
(-2 + ) - (-2) = 1 2 + 11
3
3
numerator into two separate fractions to
(-2+)-(-2) = 132+131
simplify completely. These are all concepts that were covered in
(-2+)-(-2) = 132 + 131
Lesson 5; feel free to review the Lesson 5
(-+)-(-) = +
notes, if necessary.
6
16-week Lesson 19 (8-week Lesson 15)
Difference Quotient
Example 6: Given the function () = (1 - )2, find the difference quotient (+)-().
7
16-week Lesson 19 (8-week Lesson 15)
Difference Quotient
Example 7: Given the function () = 1, find the difference quotient (+)-().
(
+
)
-
()
=
1 +
-
1
1 +
-
1
+ +
(
+
)
-
+ ( + )
- ( + ) ( + )
- - ( + ) ?
- 1 ( + )
- ( + )
- ( + )
Answers to Examples:
1.
(+)-()
=
5
;
2a.
(3 + ) = -2 - 7 - 5 ; 2b.
(3 + ) = -5 ;
2c.
(3 + ) - (3) =
-2 - 7 ; 2d.
(3+)-(3) =
- - 7 ;
3. (+)-() = 2 ; 4. (+)-() = -10 - 5 + 10 ; 5. (-2+)-(-2) = 1 + 11 ;
3
3
6. (+)-() = -2 + + 2 ; 7.
(+)-() =
-1 (+)
;
8
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.
Related download
- offsets and recs what s the difference
- electric potential difference
- what is the difference between sensation and perception
- sd for difference between means
- a difference quotient is an expression that represents the
- the difference between genesis 1 1 2 4 and genesis 2 4 25
- difference between mobitz 1 and 2 key difference mobitz
- difference between phase i ii iii trials
- difference between topoisomerase i and ii key difference
- ch9 testing the difference between two means two
Related searches
- find the difference quotient solver
- write an expression calculator
- the represents the domain of a function
- which histogram represents the same data
- symbol that represents god
- making a difference in the world
- how to simplify an expression with exponents
- a give the molecular formula of menthol b this molecule is an alcohol classify
- assume that an is an arithmetic sequence
- how to use the difference quotient formula
- difference quotient calculator
- step by step difference quotient calculator